---
title: Building a Meteor Fall game with JavaScript [livestream]
slug: building-a-meteor-fall-game-with-javascript-livestream
published_at: 2021-03-07 11:09:10 +0000
updated_at: 2026-03-04 20:14:25 +0000
summary: 
description: In this episode, we build a simple rock fall game with emoji where rocks fall from the top and the ship (🐛 or 🚀)  attempts to ignore falling rocks by moving left and right. We use plain vanilla javascript and HTML canvas for this one.   Code: https://github.com/cjavdev/rock-fall
tags: [javascript game, rock fall game, meteor game, javascript, livestream, pairing with kids, pair programming, emoji games, caterpillar rockfall, logiebear, goofybud, cjav_dev, Building a Meteor Fall game with JavaScript]
views: 615
author: CJ Avilla
url: https://www.cjav.dev/videos/building-a-meteor-fall-game-with-javascript-livestream
youtube_url: https://www.youtube.com/watch?v=o5CWxjV5Le8
youtube_id: o5CWxjV5Le8
embed_url: https://www.youtube.com/embed/o5CWxjV5Le8
thumbnail_url: https://i.ytimg.com/vi/o5CWxjV5Le8/hqdefault.jpg
type: video
---

# Building a Meteor Fall game with JavaScript [livestream]

*Published: March 07, 2021*
*Views: 615*

## Watch

[Watch on YouTube](https://www.youtube.com/watch?v=o5CWxjV5Le8)

[![Building a Meteor Fall game with JavaScript [livestream]](https://i.ytimg.com/vi/o5CWxjV5Le8/hqdefault.jpg)](https://www.youtube.com/watch?v=o5CWxjV5Le8)

## Description

In this episode, we build a simple rock fall game with emoji where rocks fall from the top and the ship (🐛 or 🚀)  attempts to ignore falling rocks by moving left and right. We use plain vanilla javascript and HTML canvas for this one. 

Code: https://github.com/cjavdev/rock-fall

## Transcript

what is up friends we are here again we're gonna hack on some some games the boys and i are gonna play around and build out a game what is the game again called it's it's a um it's a it's called it's called meteor fall meteor falls so what happens is meteors meteors fall and you're in you're a small tiny block and and we might be able to it might be in a tiny caterpillar mode a tiny caterpillar emoji okay yeah and then wait that is not a creeper your minecraft shirt is glitching out yeah we can see that we can see the throat right through your stomach to the couch behind you okay all right so and um and then come in you move um left and right um you move left and right for to dodge the dodge to dodge on um at the cardboard the dodge meter if a meteor hits you mm-hmm you die it just says you die and reese restart restart okay so let's do it let's make it um let's see oh gosh uh let me clean this up a little bit i forget what was actually running here okay so we want to create a new thing uh what are we going to create oh gosh i term is closing on us uh friday march 5th today is that today oh that was the last login was yesterday okay so then all right hold on hold on okay so cool all right let's see i wanted to just like get this screen kind of like split like maybe half split like this and then can i tell you how so um so um go over the go over the full screen button and it should say um put screen to the right or put screen to the left okay so this looks pretty good though because we can see we can see the browser and we can see the terminal so why don't we do um uh let's see actually yeah here okay um all right so we're gonna make a new folder called what's it gonna be called actually why don't we use um yeah let's just we'll just make a new yeah you want to use react well i think uh i don't know if we actually need react because i think we can use yeah i think we can use the html canvas and javascript what is it called again meteor fall easier fall media or fall okay and so we're gonna have a index we need um yeah i have two live things we'll just say index.html what do you mean why is there two live things okay um go back and there's one that says why and then there's another thing that's live and oh i think i messed something up um so let's set the height and width and get just to get a canvas an html canvas on the page and let's see if we can tell what that is border equals one maybe and try to just refresh and see if we can see the canvas oh wait we're not even we're not serving anything meteor fall me t or fall and then we wanted to say like um we want to serve this why don't we just use like http server this is like a node package that you can install it's called http server and it just fires it up so you can have a localhost 8080 that's just serving those static assets there okay so we at least the title is right uh okay so let's see if we can find our canvas here on the screen so if we inspect okay we do have a canvas and it looks pretty big um all right so yeah i i think a couple of things we're going to need like we're going to need to figure out what like how to how to style the canvas how to work with the canvas how to draw things okay so yeah why don't you think of a color um no no there's no way you can find them the color is black it's in space we need it measures here ours are in space measures are on space meteors are in space yeah okay so uh so let's let's write some javascript canvas okay so we'll just call it like um game.js maybe and then from game.js we'll implement our javascript and i just copied and pasted this from w3schools but yeah let's see okay so our canvas is back and we want to grab our element by id and next so we don't have okay so we need to give an id to our canvas so let's give it id of game canvas and then refresh the page and nothing happens oh that's because this is loading before um before the canvas was on the page okay cool so we've got a square we've drawn a square on the screen it's too small okay so how do we add a border uh ht or like how about we make like a fill background of canvas um so i haven't worked with html canvas in a really long time so okay yeah so you just need to like fill the entire thing let's see if this is blue though i know uh fill style blue um why isn't that working oh we've got some errors here in our javascript so canvas is not defined oh right because it's called it's just called c okay let's see all right so now we've got a blue what color do you want to make it black it has to be black because is there a blue outer space i don't know i did different whole universe okay so now we want to draw we want to draw the ship right so one thing i think we need to do is probably start to organize our game a little bit like into some what if we've what if we found a game emoji a game emoji emoji ship emoji [Music] on html canvas i was thinking what if we make it like the rocket ship emoji oh yeah i want to be a rocky chip i want to be an animal in i want to be an animal or something wait the first ape the first fruit flies in the first dog it's not going to be like something like that let's see if this works ooh canvas is not defined again yeah okay let's just make yeah no that's fine just to see and change this to c and it should make that emoji thing in the middle okay so that's kind of interesting right it has like these little things and then we can just what if we just change it to like um a caterpillar here we go rocket ship thing i don't want to be a rocket ship why not i want to be something like like like a baby caterpillar okay do we have a caterpillar emoji let's see no we have to make it let's take some more hug oh bug there we go how about this one there's your caterpillar emoji right that's it there it is i can't i can't see it has to be bigger okay um so how do we make it bigger what is that slash two divided by two is is to put it in the middle of the page um but here we go it should be it should be at the bottom you can dodge out of the middle yes it okay so we're gonna have to figure out how to put it on the bottom then right we have to work with those numbers oh there it's massive um we need a little bit smaller okay so let's figure out how to how to make it um how to draw it so let's let's uh let's actually make some classes here let's make some classes so let's make a class called uh pick a class called um ship right and constructor will be um the like uh symbol and then we'll just like pass this dot symbol equals symbol and then we'll have like a render method for our ship that will tell it where where to like actually punch it like that that's a true bigger symbol that's a caterpillar because the meteor will be too small for that thing okay so then we have a class that is like game and the game has mirrors though where i know that's okay that's okay that's all right um so i i just didn't clear them so so if we move this down a little bit and refresh yeah are you kidding me that caliber is like humongous so the game constructor let's say the game constructor takes in like reference to the canvas [Music] um when we get when we get there bud just a sec give it a sec so this uh ctx is canvas.getcontext2d i think maybe i don't know and then i think we're going to want like a game.tick or something where it like changes with the caterpillar or um i don't i don't know so so the game do we want to like have each of the objects have reference to the game to the canvas's context so it knows how to draw itself on the canvas or we want to have like a different view object that's responsible for rendering it so like right now right like if we if we make it so that the game just colors it's it can like set up the fill style and the background right so then we can have this part here um this earlier it's gonna be like underneath me like always walk like if hit bottoms up do you have multiple so he's having multiple um falling at once but we could actually put an invisible black line in the middle of it and it could be like when the object hits the bottom um it can't be in the middle of it because the color is at the bottom so that's the smash so so if you if so if this thing if scarborough is going to die then the meteorites will smash the power for the camera yeah so should the game so the game should probably know about the ship and should probably know about each of the or like how many maybe like how many yeah i should probably know about the ship and so we can say this this dot ship is ship and then ship is going to be uh your caterpillar thing so then we're going to say like this are we ever going to do this.render and that gives us back the uh yeah how do we want to do this [ __ ] because that's what it i thought that's what it was no it's not it's not a ship it's just a cowbell running around okay well that's like what it is though right like so then we want to say at the end we're going to say something like um b is an uh new game and we're going to pass in the canvas and we're going to pass in a ship and then we need a con ship canvas is defined as c i know you're right yeah so i'm just going to rename this there are so many so we don't need the context anymore we already have that we didn't actually need that and then we didn't use that okay so then okay so it's not working anymore right because we're not actually rendering anything so we call game game.render what does that do the game.render is failing because c is not defined and that's because this should be like this dot canvas.width and height but i think we i almost wonder if we might want to pass in the height and width or something to the game i don't know all right so then um chip dot render i feel like uh we should call we should make like render space or something and then this would do these two things and then render ship or render like calls this dot render space and then ship that render um and then maybe we have to pass in the context this dot ctx and then the ship figures out like okay i'm going to set the where i'm going to set myself okay c is not defined uh right because that's going to be the canvas so it's right there by width and height yeah but that doesn't know it doesn't know about what the canvas is so right here c c is supposed to be the canvases height and width um so i think let's just let's just hard code it height is um what is it 300 and width that is 400. dad this has to be at the ground you mean the cairo has to be on the ground of the space thing yeah so we need to figure out how to do that so um do you remember do you remember what you changed to move things around remember what bits you're supposed to change to move things around on the screen so right now right it's rendering at width divided by two what if we just do like width or height where do you think it's gonna go i don't know i think it's gonna go in the corner i think maybe this corner or this corner let's see oh it's gone yeah so if we do like width minus a hundred eight minus a hundred right okay okay so now it's over here so if we say height minus 200 does that go up okay so then height minus we need like 10. we need height minus we need height minus uh we need to make the caterpillar smaller okay so i think that is defined by this font size here so let's make it half the size oops if we make it half the size and then refresh oh too small let's see that okay so serif doesn't matter okay so 50 pixels that's how big it is should we do 40 or what do you think is that good size or what 40 is better okay and then should we have it be 10 10 off the ground or let's try five see if it hides below okay so it's kind of on the bottom okay and then the width right i think this is actually going to be based on like your arrow keys right when we go right and we go left it's going to change like where the ship is yeah okay you mean caterpillar where the caterpillar ship is okay where the bug is okay so let's say that the bug is going to start start out at um either one of the corners so yeah we almost need like this dot x and that's going to be like our left and right position so if we start off this dot x at width divided by 2 and then here we just render with this dot x and then we can change that as we move the ship around okay so he starts in the middle but we could technically start this at like a random number or something i said i want to start in one of the corners so dad are we ready for it well let's look around are we ready for this ship to move around uh so let's let's see oh that's too far in the corner let's keep it let's keep it in the middle for now and then we can figure this out later okay lookie because okay so he's starting in the middle and let's get it so that we can make our arrow keys go left and right i know i'm actually making it easier because you use your mouse use your mouse it'll up and down diagonal no we're just doing just the the position of the mouse okay so let's just let's just see let's just see so if we think it'll go up down no we're just doing x well we can do we can just do like the x and y position of the mouse so let's try to figure out x and y is everywhere i'm sorry just the x position you're right you're right okay so set interval it takes a function to run and um we want this to run let's double function so there's two pieces over on top see that there are two of those um curve things two parentheses yeah so the first one is to call the set interval function and then the second one is to define our next function we're telling it that it doesn't take any any arguments here and so what we want to do in here is we just want to console.log the mouse is x position so i don't know have you remember we were learning because of the luck um we did not p5.js and the other thing so we want to get the mouse position uh how do we do this um handle that goes everywhere on mouse move handle mouse move so then we do we want to change what okay wow this is harder than i thought it was going to be yeah it's a little harder okay that's all right that's all right right yep so we can say okay so oh cool it probably so yeah we do want to use the on mouse move event okay or do we want to use the yeah okay so let's let's just get like a basic thing going that will move it around so document dot on mouse move is a new function that will console dot e so the this is going to be past i think the the argument e so then if we refresh see how in the console down here as we move around it's moving a ton right character is amazing yeah i know but we're just trying to figure out where the mouse is right now i can tell you we should do um dot x because there's a dot x thing and we could do this one mouse x and mouse y well y goes up yeah so that that mouse x and mouse y is only in p5 js that's only in processing we're just in raw vanilla javascript right here wow so but i think we've got it so if we if we add the on mouse move directly to the canvas then it should only track mouse movements while we're inside of while we're inside of the space and then when we're outside it won't move anymore right so if we move around in here it moves around and we move around here it doesn't ah chew excuse me thank you okay so let's see so client um so which one do we want screen x screen y client x client y uh layer x offset x page egg oh wow there's so many there's so many um things relative to the thing okay so yeah which which one do we actually care about that's the question well let's just call uh let's just try messing around with it and saying like um i hope you don't crash e dot well we're not gonna do that uh client x let's just let's just log client x okay so over here we're looking at like low numbers and over here we're looking at high numbers right so we want to take client x and we want to pass that into the ship so that we're rendering the ship at that position so i think what we want to do is say when we render the game when we call game.render we actually pass in the mouse's client x and y so we'll say e dot client x and i think we might want to pass more than that but let's just start with that and then here we can say in our render method we pull off x and then we want to say this.ship.render or this.ship.move move um and then we'll pass it in the x move two and then we'll give it an x this dot x equals x let's just see what happens um so then here yeah here we can say we can actually say like uh ship dot move to eda client x where is it oh this right here okay so yeah i mean um that might have been from earlier hopefully we're fresh now let's see yeah so if we clear that then it's gone yeah no errors right now so um all right so i keep second guessing myself so i'm saying shipped up move to and then we're giving it an x then we're calling game.render that'll render the the ship so let's let's check let's check it out let's see what happens oh type error cannot destructor oh seven errors now okay guys we got seven hairs okay watch oh whoa up and down doesn't do anything yes is that what we wanted okay but it just got out of the screen it doesn't go out of this oh it goes out over here but it doesn't go out over here in fact like it kind of bumps up against it yeah okay but hey look at that it's moving around right yeah but look if we um later in the day okay so maybe we should only let it go move like we should say like only if x is less than or equal to um width minus 10 or something or we'll only set x if the if the width is minus whatever okay so that's that's pretty close to what we want y yes raise y oh i crash into one yeah so i think since it's a 40 pixel since it's 40 pixels like the emoji is expecting to be in the 40 pixels so maybe it needs to be 40. i don't know let's see oh yeah totally okay cool cool cool all right so now what we need to do is drop rocks on his head no no drop asteroids and you have to in any directions yeah let's just do an emoji okay so class uh before i say it falls on his on his head is it an asteroid or is it a meteor meteor what's called okay meteor yeah oh what do we call it just rock this is definitely going to be going like this is i i thought this video was gonna be as shiny as it probably is i don't know um okay so this dot symbol is equal to symbol and this dot x is equal to x and i think we do want to pass in no like a a location just like a random location so let's passing random well let's let's actually just take in the x location um and then we need to define a render function for this too so the render function is going to be let's just change the symbol to like um rock is there a rock thing no uh can i try meteor well how about we just make it a whole planet no no oh asteroid look at that it's totally an asteroid uh it's gonna be like going the wrong direction but that's okay all right so well we could actually we could actually turn can we actually just turn it somehow um i don't know if she like rode yeah rotate it i don't know okay so then we want to do 100 degrees i don't i don't know how you rotate like i don't know if there's like a rotate thing uh yeah so can't can you see if there's something other are they so hold on let's let's we've got our game is our game is constructed of the canvas and the ship and we need to pass in okay the job they need that's the jolly thing grayson and these from minecraft that type of drama symbol is the same job symbol that grace me had been searching up when we were looking for minecraft where where are you talking about that on the dolls this thing up here oh that symbol is stack overflow that's stack overflow that's good yeah that's this is the website that has all of the answers when you're a programmer uh it's like a help website so i think what we want to do is like um over time we want to make new rocks and we want to like drop them right yeah so how do we do that we need them to be rotating forever okay so let's just say game dot drop rock or something or like he's going to the um asteroid ring around out of the saturn and it could and they could end up like flying around in circles let's call it drop rocks and then um that'd be awesome yeah and then when we call drop rocks it will create new rocks and add them to a list of rocks so this stop rocks [Music] for is at once so the game doesn't crash and running rocks up here at once so let's push on a new rock and then we'll say oh let's actually make this here and then we'll make it render we'll make another render or no we'll just call this at rocks.map we want to go we want to like iterate over each of the rocks for each and then for each rock we want to call rock.render and then probably have to pass in this.ctx okay so um we're pushing on a new rock and when we push on the new rock uh this dot y goes y um or no this is gonna be zero i think yeah let's call it let's call it 50 just so we can see it um nothing okay so what's happening here so there's we're calling game.render and when we call game.render actually we need to call it out here too game.render when we call it out here we're iterating over each rock and then oh you know what we never called drop rocks so game dot drop rocks and for now it's just going to drop one but like we could call it a few times um yeah but it hasn't dropped in multiple directions i know not one yeah so we okay so we need to pass in um um drop rock over a thingy when it is the nevada flag yeah so that's our ship and then our rocks um let's see rock doesn't mean you're saying this thing what no okay wait how did you get the right one uh i don't know i thought you got the hands oh no okay so then here instead of five years maybe let's test that in a minute because i think we might be able to do that with css but i'm not sure let's see css cascading style sheets it's for styling stuff yeah so we've got our canvas we've got our ship we've got our game we're calling [Music] so the rock right now needs to be initialized with um the symbol and then some x so let's do width divided by two have you ever heard of rock you've got a rock on the screen it's so good no it's okay it's okay we're getting close because every now we need now we definitely need like a tick so like set spawns every few minutes well this is gonna say like every second or every f half second like do something and the thing we want to do is all the rocks on the screen need to move down and down forever until we get out of the screen that i think we need to make a special line like that the caterpillar can't go with the rocks and glaciers it's okay it's going slow because we're only updating every 500 every half second if we move this down to like 50 it should go way faster yeah okay sometimes you see even going in front of the mask yeah but what i was trying to figure out is like okay we're rendering the game every time we call render game do we want the rocks to go to move down a little bit um so then this becomes like uh no we want we also want the sizes because it's really different right yeah we want sizes to be different can't we also walk and we also want them falling immediately so when spawn fall down when spawn fall down once bone fall on one spot fall down yeah we'll see oh gosh we need to make it so um soon if it hits if it hits um if if his caterpillar uh-huh if it hits the caterpillar [ __ ] then can i do the typing i know hey i know if this is hit [ __ ] is me there ship then hit and then and then not i'm not gonna do that or else else you just else disappear okay so you wanna you you wanna try it so that it's um all right so right now we're falling too fast i think let's see so if we if we do that okay so we'll have to mess around with this that's way better the speed let's let's just make it a constant like once like const is like a variable that you don't ever change that you're not going to never change it went to the thing we love that don't we we do yeah okay so then the other thing is that like once they go off the screen uh i feel like we have to we should just like destroy it but right now we're not doing that so yeah it's just gonna make like a whole bunch of objects but it probably doesn't matter that's fine um okay so then what do we what else do we need here um i think we need to render like a few more rocks like we need to right now when we call drop rocks we're only adding one new rock smack in the middle um i think we should add like a random number of rocks like maybe one or two or three or four or something five or six or seven or eight or nine uh-huh four or four what what is the javascript random thing how to find a random number in javascript no it can't be random numbers math.randommath.random i couldn't i thought it was like on window or something so math.random gives us a random number between zero and one i think zero and one yeah so we take math.random times and then whatever our number is oh oh we can only go up to four it's gonna go up to four okay so so we'll do up to four oops and then we wanna say like we don't want all of the yep i keep saying my thought random equals 10 equals 4 equals 10 equals 4. so here we go this is this is good right so it's either one or it's two or it's three or it's four so this is it should work fine some this will give us a random number so like uh const num rocks equals this so then we want to iterate we want to say like 4 let i equal 0 i less than num rocks i plus plus for that many times add a rock and we want to add it at a position out at random position yeah so what like the maximum is going to be the width so this one is going to be like const x is equal to actually i should say both yeah it's raw javascript and really hard html writing uh i'm not sure what you mean okay so this should give us an x again a decent x oops wait if we did like x math.com nothing happens we haven't so we need to add collision detection so if we get if we get crashed into like this too slow let's see okay if we go twice as fast okay okay so sometimes there's one sometimes there's two sometimes there's three cool so this is i cannot go below one this is good this is fun right this is fun okay so the very first time we render oh you know what we're not passing in x when we first initialize the ship um so let's yeah let's put it at uh well okay so here's the other thing is that we can this function that we wrote that has this random stuff right this uh this thing here gives us a random x so why don't we make a helper function that's called like const random x and that will uh return same thing that we just wrote down there okay and then we're going to need this for a few different things right and then we can say random y actually no we don't we don't need random y because we're going to just why is with um capitalize oh that is that is a good question so with i capitalize with because it's a constant and we don't want it to this by writing it as in all caps screaming snake case sometimes they call it screaming snake case because it kinda looks like a snake with like this underscore in the word so when it's screaming snake case that tells you that okay this this this variable that i'm using should not change it probably should not ever change so when we initialize the ship now we want to call get or like what's it called random x so then random x is just going to return a random x value for us and we can do that here too so this will give us like random throw in the middle of the screen uh no so like see watch watch when i refresh now see the caterpillar is showing up in a little bit different places every time and the rocks are showing up in different places and the rocks are different yeah and the rocks are all different okay so okay now i think we need to get the css before we get to these so so they are so so they'll be spinning so they're spinning yeah yeah because they're going in the wrong direction then we have to make them going diagonal let's see if we can figure that out rotate rotate text css on canvas let's see if it recommends using canvas or using something different context.rotate oh interesting translate rotate okay so you rotate the whole let's try it okay so when the rock before we before we render the rock we want to call ctx dot rotate um mass pi well okay we want to rotate like pi some fixed amount i don't know let's just see if it rotates something and then oh it did kind of glitch let's let's see no we need to slow it down slow it down is it in radians or something or like what is this see if we can turn it sideways oh look at that that one is totally rotating or they're they're they're rotated i don't know oh you know what's happening is it's it's changing the orientation every single time oh dad it went sideways wait did it yeah it went sideways okay now it's just a caterpillar there's another cat everything is totally glitching out it's totally glitching out okay so i think we want to like wait i think we want to rotate back to zero after we've rotated it for oh nice okay i don't know why it's flashing but wait wait oh that one it is going sideways it is going totally sideways yeah you see where where it's go we're going oh that's because when it's rotated it's rotated just a little bit it's instead of down like down is now rotated yeah let's see so we could go forever again okay problems didn't do anything okay good shot that buzz there's only one that's me too easy of a game and then like and then like you're like oh this is too easy here let's just let's just change it from being that orange thing to being like just a uh something else okay how about a red dot perfect that kind of looks like sort of uh like isn't there there's like red there's like some sort of sun or something it's like a fancy red sun okay so all right so what else do we want to happen wait it could be like that could be the part of the scrolling game so i think the other thing that we want to do is like we want to drop new rocks randomly forever yeah and forever yeah so i think randomly yeah i want to say like set uh interval well actually yeah why don't we do it this way like um no we can just do a different one uh set interval every two seconds we'll call drop rocks and then we'll okay okay oh look at that oh okay so this is gonna actually be pretty tricky what if i tried to like do a trick and come in here and then like okay all right so uh but the fall speed has to be faster the fall speed needs to be faster since the boy okay so we'll refresh this oh man oh man okay so should we we could make it we could make it too like if you've gone a certain amount of time then we're like we drop more rocks on you or something like here we go okay now get more rocks more frequently oh there's no time limit yeah okay so then what else should we do oh man oh man oh man oh man okay let's work on collision detection logan what do you say okay so we actually went what if um when the media yeah the uh caterpillar it actually turned into a red dot oh interesting yeah okay everywhere and you can put your hit and then you can close um and then it's in it hey dad maybe we could do this maybe we could make what what when did we start huh do all this coercion when hit restart like when you oh i see you start yet when you when you but if you die when died you say you die hit respond and then this whole games happens again okay so this i'm noticing something and because we're just calling methods only on the game inside of here i think we actually might want to move this logic inside of the game itself so inside the game we can create new yeah i think we want to create them inside of the game here so that we have access to them so that we can clear them when the game is over so i'm going to say this game interval and this dot rocks interval are going to be new or they're going to be the return value of these functions that are calling render and drop rocks and that way when we when we try to do a detect a collision um like after that we should say like after right after the rocks fall say like this dot game like is game over something and then we can say is game over is true if uh or maybe yeah so like if game over then we want to um oh yeah hold on let's see so this is actually render we don't actually want to do it in render we want to do it inside of like what are those different colors for what do you mean on this in the text like how this one's white and this one's blue and this one's orange and this one's green those are to help you know um it's called syntax highlighting it's to help you know what's happening on screen isn't that cool that's why i'm like yeah like is it a function yeah like see how this is green if i misspelled this and i had like x then it doesn't turn green so i'm like oh one of those three is different and then you know like okay just to make it the same i can just try to make a random a random code sentence that won't affect her uh a random code sentence it's a comment right yeah okay so all right let's let's we need to figure out if if the game is over so how do we do that well we need to check like if any of the rocks have fallen on the ship wait wait we could do if rock touches caterpillar ship so both ship and oh actually no ship and so rock has x and y but ship only has x so well it's y is kind of just hard coded to height minus five so why don't we just set this dot y is height minus five and then we can say this.y here and then what we can do is now that both ship and rock have x and y we can just check and see like if they're too close and if they are then we'll consider them crashing to each other and it appeared like sideways uh the symbol got glitched because simple never got glitched the symbol was because because both of our things because both of the both the rock and the ship they're both symbols so it slammed out and it thought the caterpillar was the lock symbol for every second okay so let's say that we have an is touching and we'll pass in i mean we can just pass in two objects a and b or we can call it like ship and rock or something um okay so we'll just say like if a dot a dot x minus b dot x is less than 10. uh or actually let's see why is the game still running we rocked it keeping our heads are you supposed to stash them okay so this is roughly what we want i think for our collision detection is we want to say like is the x for one object minus the b for one object almost the same and by almost the same i just say less than ten but the problem is that if one of them is negative if we get a negative number then it's not going to actually work because then it'll be way less than 10. so i think we want to use like math.abs right so if this is negative 100 it actually is a hundred so abs is a function to find the absolute value of a number abs abs yeah and absolutely so grayson what is the absolute value of of negative one um below one is one so the absolute value is basically like one so so then the the absolute value of negative one is one and the absolute value for one is one and the absolute value for like negative 1 000 is 1 000 is 10 000. and the absolute value for negative 90 is 90. the absolute value for 80 is 80. so like the numbers on the left some of them have a minus and some of them don't have a minus all the numbers on the right are these are all the absolute values and the absolute values never have a minus okay so it's like you take you can take any number and get its absolute value by remind removing the minus if it has a minus sign or by just taking if it doesn't have a minus sign you take the same number so what is the absolute value of 10 grayson good the value of negative 10. absolute value of negative 10. good absolute value negative 100 good nice so now you know it's absolute value so we we have our like is touching or we have like is touching so what i think we want to do is say like um in our function that's rendering here i think we want to say like if uh if is oh wait no if uh not vista game over then we render it and then our game over function it's just gonna check to see if any of the rocks are touching the ship aim over maybe is and then is game over and then we can and then we can play the game maybe yeah we'll see we'll see let's see okay so we want to go through all of the rocks so this.rocks.4 uh is that what we want to do or maybe we should use the for loop again because we want to break out of it right yeah so uh for var rock of this dot rocks console.log rock let's just make sure we can loop over them there we go got all our rocks and then we want to say if is touching rock and ship then return true and if we get through all the rocks and none of them are touching the ship then we return false oh we're missing a parenthesis here okay and then we refresh and then we'll push it out how do you make sure that no one does the same thing wherever good question so localhost this local host is the host name for my computer and 8080 is the port that the program this http server program is bound to oh nice the output the log output that's funny um okay so the next thing what do we want to do next we've got our is game over if they're touching we return oh it worked i think it worked no it didn't work let's see okay crash hit each other come on oh great it worked and then in the middle it should say you died you died okay all right so fan if the game is over but if the game's not over then we render else we uh we want to say clear interval we pass in this game inner wall so the game stops and we want to say and we want to clear the rocks interval too otherwise it'll just keep drawing new rocks on the screen well that would be cool as you're oh do you know it's crazy oh my gosh okay so let's see oh like actually okay okay again [Music] okay so the game shouldn't restart now if even if i move around and stuff because okay um all right cool so we've got it we're colliding what else do we want to do should we get like maybe we should get points every time yeah every time every time rock passes them okay okay but but the rocks can actually get points okay so we'll we'll keep a score then this dot score equals zero oh you want to do okay here yeah you you try it okay all right let's see it what you got see what you got oh man oh wait i wasn't ready oh yeah okay yeah the other thing is that like i think it might be too easy right now our tolerance of 10 pixels might not be enough it might not be intense enough right yeah what do you got um actually the more what if we do the more points um the more points the the caterpillar gets the more harder it gets oh kind of like just okay well oh i actually alright well if it's under you can easy it's too easy we gotta make it harder it's too easy okay right it's too easy wait okay okay so let's make it let's make it harder so we wanna let's make the fall speed like five oh that's harder it's harder but it's not impossible right yeah because it because you can actually just get immediately get through and also um okay and then your bottom all right so then let's make it also so that every time we drop rocks we also increase the fall speed oh now you're right all right so every second it'll get harder all right oh oh i'll [ __ ] okay so it's getting faster is it getting faster no it's not okay so this still feels pretty easy yeah it feels pretty easy we gotta we gotta make some gaps tightened up well yeah wait actually there are some guys all right so let's try this so then every time it drops rocks it should really pick up speed oh wait what is this oh i can't change a constant excuse to do lit yeah oh there we go oh no baseballs oh geez oh geez okay all right let's see okay okay okay okay okay okay thank you fast all right that's almost impossible okay okay all right all right let's see let's drop rocks every every and then we'll only increase the fall speed by like 0.1 every time then we get more rocks oh it's like a trail oh okay it's kind of like a maze yeah we can call this the maze game instead okay so 0.1 is probably still too much still not enough all right let's go faster so okay that's enough you think so yeah that's enough well wait real quick um it doesn't look like okay it doesn't really look like it's falling it just looks like you're a zombie okay and then let's also increase yeah okay so i did die all right so let's make this three and then we actually we should do something if touching the red i think the whole screen goes red we're like roll everything like the bread hey we do is touch pressing make screen red yeah make canvas red so i'm thinking about making or i'm making this drop rocks function instead of just dropping one two three or four rocks every time we're gonna pass in uh drop random rocks yeah or like an n and then that's we'll go up to n so that as the game goes on we we keep increasing the fall speed which is now like really becoming like the difficulty let's just change it to like difficulty and then so we're starting out on difficulty five right oops ball speed is not defined well if we want really dad look at how many years yeah because every 500 seconds okay here we go here we go so now it should just get harder and harder like oh oh man oh man oh okay i can't see that so it's okay so it might be too difficult now it's too difficult now okay so then let's tweak the points okay let's see so we want to make points every time you every time you pass or ask or should we just display like the level like yeah it's we can call difficulty the level and every time you kind of like pass a level right every time you we increase this oh come on that was all right didn't you need anything i think our collision you can actually glitch it if you um just go fast yeah go fast okay so then you can get you everywhere difficulty if you delta what's the delta this is like how fast the difficulty changes so right now we're changing it by 0.1 that's like how quickly it adds more all right so the next thing we wanted to do was display let's display the score yeah so we could do when rocks on screen all right so then when we rendered too i wonder if we should render this.render scoreboard or something i thought i thought css um well we did we were going to try to rotate something and then we decided not to so then if we write if we do text again how do we do the fill text thing so we need to customize those balls why they're red they need to be gray what no asteroids meteors are gray not red they are yeah yeah they're red they are red yeah but there's a little flaming part out of it that makes you look like it's like fire then we have to break apart it to look like they're really fireballs yeah okay it is called meteor so yeah actually our a character could be an earth that has arms and legs and equations so since these are since these both became um let's instead of const i don't think these are actually constants i think they are variables that belong to the game so let's take them in as like difficulty and difficulty delta and then we'll use those here just difficulty difficulty and this dot if delta equals this uh okay and then here we'll change it this dot diff multi equals plus equals this difficulty delta and this will make it so that it keeps increasing the same amount if we initialize game with what was it again five and 0.1 and let's just see oh what do we break what do we break 156 errors this dot oh this is going to be this dot difficulty 2s ring and we'll print it at like 20 20 and we'll make it still style it i think let's see okay so there's the score it starts out as five yeah but you can't even see it yeah i know i get 10 and then we'll put this up to 50. all right where is difficulty oh plus equals oh you're right okay so 10 is too small then huh try that's probably right somehow um i think sometimes the command space okay so the difficulty is like increasing right people are they where are the meteors uh they're not falling right now all right okay why isn't getting why is he giving us a score because the difficulty is increasing but there is no what all right yeah we broke something so let's figure out what's going on okay this is the light the red balls of fire okay the meteors are spawning right there no because they should be coming down the screen right okay so we're passing into the game we're passing in the canvas the ship five and one wait is it behind the canvas can we break something and put some ears behind the canvas no are you sure then no no i didn't say no so we're dropping the rocks and then we're saying this.render oh we'll be wrong okay so it does say dropping rocks well it's way too quickly let's see how many it's supposed it thinks it's dropping five six six seven that's how many it thinks it's dropping but we don't actually see any dropping right so if we go into drop rocks um we're running this every 100 milliseconds or we're increasing it 0.1 every time all right let's try this again one four five six one okay so that's the right number of rocks then it's pushing them on there pushing on the rock and then the rock is saying i'm gonna pull that oh what happened no that should be fine right wait rotate we don't need to rotate this oh fall i removed okay this dot def old t there we go all right so now it's interesting ah i introduced a bug to my bug little bug run away little bug run away okay we're level seven we're level seven we're running so fast we're running so fast nothing will catch us now nothing will catch us now eight eight point eight nine oh my gosh oh my gosh we're running away we are running away oh man oh man oh man oh he glitched it okay okay let's let's make it so that our difficulty doesn't print out as decimal so meth dot seal again the ceiling of this and let's see yeah five six all right we're on level six level six mage all right nope oh man oh man logan this was a fun idea bud cool game idea all right level eight level eight are you okay level eight level nine oh try to break your high school record okay all right 11 11 is my high score right now okay okay oh gosh oh gosh oh oh oh oh oh oh wow oh yeah okay okay all right okay okay all right holy smokes they're like separating out because there's they're it's getting it's falling so fast now that there's like more things oh gosh all right here we go here we go oh it doesn't work on there you got to keep it on here ready get set go [Music] we with it in order to die what dude nice 10 level 10 oh i bet my school last time was at like level six okay i think hold on i have some modifications we should make real quick all right here we go i'm really at seven how did it go all the way to seven i was at six earlier well it starts oh it's doing superstars i know that's a weird die right i think because i think i think the position is actually like the position of the caterpillar is this corner this top left corner and i think the position of this one is like maybe i don't know over here yeah so like we can i think we have a couple modifications number one i think we want to put out actually try something guys allowed me to right through them yeah i know that's what we got to improve is our our collision detection is pretty flawed yeah okay we actually actually did score yeah actually no just stay here because we we had like tons of snacks but we already had tons of snacks what i just finished 12 minutes no yeah actually you had lunch and then you had snack right when we got in here just hang out with me for a little bit okay all right so it's now printing out score but i think we want to move the score a little bit up and over um let's see if that blame guide and all right yeah but then we have to make the you have to make the score opaque if you know what i mean oh opaque you mean so that it's on top of the things that are falling down yeah on top of the asteroids so it's so the asteroids can't just block it like oh it's your score these asteroids people blocking it okay so uh i think that might have to do with like the order that things are rendered yeah maybe so we want to render this scoreboard last or something let's see oh yeah did it work yeah it worked nice okay wait wait wait wait wait um i tried to skip levels okay well hold on i was trying to figure out like if you okay here's the other thing we can do we can add arrow keys should we use the arrow keys yeah left and right so we can move you cannot what if we so how do we listen for arrow keys let's see key we can do like key up or something yeah or maybe key down should we do key down key no switch left and right key press key down or key press which one do we want um okay so let's just try it so if we say document.add event listener key press and then we just do like uh right and left console.log e it's like trying to figure out what why is it key pressed because we can't play this game on the phone it's also like for phones for kindles um oh that's weird and laptop so it only it's only actually getting real actual keys not [Music] only do you need keys on the screen we buttons on screen to press yeah is this huh key press you should use key down because key press will ignore arrows oh weird okay so key down all right so that's the key that's the javascript event we want to listen for cool oh nice okay so it's left left left left left right okay so arrow left is what's key is so if we say like um over here if we say if e dot key is equal to arrow left why isn't you joking what is it um why is it a huge triple triple equals so yeah so so e dot key is this this key right here on the event so what's happening is every time you press the event it's like when when clicked when the key is clicked then this event fires and that event object is what we're logging right here has a property called key right in javascript when you're checking if strings are equal or values are equal you can either use two equal signs that say like is this equal to this and you can do it is yeah and so the difference is that like if you have if key was a number like over here we have location right if we did like e dot location and we said if that is equal to um the string zero then that would fail because it's not completely equal to zero because it's not a string it's a it's a zero but it's not a string zero so if you want those to work you can just do two equations um for a minute ctrl ctrl key it kind of looks like crikey crikey crank e crikey like from australia crikey oh crikey shift up move right uh okay so now we instead of move to a specific x we're gonna move left and right so we'll say ship ship class ship so we need to add move methods to the ship so move left and move right so if we're going left we need to change x how do we want to change x if we're moving from over here this way so remember over here is like 300 and over here is like 10. so if we're if we're if we if we hit the left arrow key where should we change the x value the x value a bigger number bigger number i think no no no left key i thought you meant reiki minus equals 10 maybe and then this dot x plus equals 10. all right let's see oh totally works but then now logan said this is gonna be a mobile app that can work for anywhere oh well then we have to figure out how to do touch we have to figure out a sense touches okay well i'm thinking it actually looks pretty sweet should we change the background color maybe wait wait you know what what if we actually what made the emote what if we change the emojis too and we could also do little dots on the background as if it's space okay what if we had like random emojis so like uh const ships is like like space junk okay so like yeah let's do like a list of no it has to be wrong with that really the camera can't be spaced okay so well let's make it so that it can either be the caterpillar or it can be something else what else could it be it could be what's like another thing what if we just search like what if we search i want to be either mars iron bars iron bars or we could just get the earth out what about like um so the first thing i'm gonna do that stuff i i just want i don't know about that stuff yeah yeah because you named it meteor fall it's supposed to be meteor it can i need it media fall so um so the meteors can be something different let's do meteors equals random that's what i was thinking was like here first that thing right there to be a rocket i want i don't want color balls to be a rocket it's not gonna be a rocket game shouldn't equal rocket ships shouldn't equal rocket but logany isn't [ __ ] cause ship equals origin damn masked up man okay so this time it's the rocket ship um that's too tall um it's the same size as caterpillar logan do you want to pick a background color what if we do a background picture and it could actually look like space because we could just um skip a lot of star wars if we didn't take [Music] audience no one's actually joining us we had we had a viewer for a little bit i don't know someone on youtube yeah if you're if you're hanging out and you're watching this and you're like oh this is fun um we've we've done a couple of these the most popular one was called we built a game in a memory game in react um but yeah we just kind of hack around and play around and learn different parts of javascript so um we do it occasionally if you find it useful or interesting to watch uh yeah please like or subscribe please give a like or subscribe says the kid um or or give us some views we're going we're going to getting money off of this what kind of money or what kind of money are we getting off this bed no we're not ranking any money yet but we're hoping to get some money off this okay off the game are you going to sell ads for trash he said twice crash or the trash bin iron bars so here let's also do like um [Music] rocks at and we're using random a lot let's see so math. floor [Music] yeah i've been waiting for you i'm right i'm ready to get something oh that's cool idea we could actually look at anything no for the video recording that's what i'm in and that why is it equals a spaceship i said i only wanted to equal a caterpillar what is that wait undefined undefined what was that what was that it was the oh whoa look at that oh look at our different space trash it's coming at you it's coming at you oh wow there's so many look at and see how it's caterpillar sometimes it's caterpillar sometimes it's the ship yeah yeah i wanted to i wanted to just become all right do you want to you want to drive are you are you flying oh man oh man fly logan fly blind logan why oh gosh oh crashing bro i'll go okay go ahead me yeah and then then then i have to pick a news right a new background or what yeah there's already fire coming out of it cool all right so should we wrap it up um so i want to see if there is any more if there's any more rock ships and and everybody there because it wasn't a different rocket ship okay well let's let's uh let's call it there and then we'll sign off all right we're gonna don't sign off yet oh what are you gonna do first has to first have to pick her a new background and have to make the rocket ship replace the rocket ship with a different rocket ship okay we'll come back and do that we'll come back and add those features in a little bit logie but for now we're gonna we're gonna call it a wrap okay i thought we'd do that bye friends bye friends bye there you go boy

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