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https://github.com/dwmkerr/spaceinvaders

Classic Space Invaders game written in JavaScript as a learning exercise.
https://github.com/dwmkerr/spaceinvaders

games javascript learning space-invaders

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Classic Space Invaders game written in JavaScript as a learning exercise.

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# Space Invaders

The classic Space Invaders game written in JavaScript as a learning exercise.

No jQuery or any other third party libraries, just raw JavaScript, CSS and HTML.

See it Live: [https://dwmkerr.github.io/spaceinvaders/](https://dwmkerr.github.io/spaceinvaders/)

[![Space Invaders Screenshot](./screenshot.jpg "Space Invaders Screenshot")](https://dwmkerr.github.io/spaceinvaders/)

## Intro

[![Run on Repl.it](https://repl.it/badge/github/dwmkerr/spaceinvaders)](https://repl.it/github/dwmkerr/spaceinvaders)

What's there to say? It's Space Invaders in JavaScript!

Create the game, give it a `div` to draw to, tell it when the keyboard is mashed and that's all you need to add Space Invaders to a website.

This is a simple learning exercise, so the JavaScript is deliberate kept all one file. There's no linting, testing, CI, or anything like that. If you want to see such patterns in front-end JavaScript, check out something like [angular-modal-service](https://github.com/dwmkerr/angular-modal-service).

## Adding Space Invaders to a Web Page

First, drop the `spaceinvaders.js` file into the website.

Now add a canvas to the page.

```html

```

Next, add the Space Invaders game code. You create the game, initialise it with the canvas, start it and make sure you tell it when a key is pressed or released. That's it!

```html

// Setup the canvas.
var canvas = document.getElementById("gameCanvas");
canvas.width = 800;
canvas.height = 600;

// Create the game.
var game = new Game();

// Initialise it with the game canvas.
game.initialise(canvas);

// Start the game.
game.start();

// Listen for keyboard events.
var pressedKeys = [];
window.addEventListener("keydown", function keydown(e) {
var keycode = window.event.keycode || e.which;
if(!pressedKeys[keycode])
pressedKeys[keycode] = true;
// Supress further processing of left/right/space (37/29/32)
if(keycode == 37 || keycode == 39 || keycode == 32) {
e.preventDefault();
}
game.keyDown(keycode);
});
window.addEventListener("keyup", function keydown(e) {
var keycode = window.event.keycode || e.which;
if(pressedKeys[keycode])
delete pressedKeys[keycode];
game.keyUp(keycode);
});

```

## References

Other bits and pieces that are useful can be dropped here.

- The sounds came from [http://www.classicgaming.cc/classics/spaceinvaders/sounds.php](http://www.classicgaming.cc/classics/spaceinvaders/sounds.php)

## Publishing

On changes to the `master` branch, the GitHub Pages site will be automatically updated.