A JavaScript NES emulator.
It's a library that works in both the browser and Node.js. The browser UI is available at https://github.com/bfirsh/jsnes-web.
For Node.js or Webpack:
$ npm install jsnes
(Or yarn add jsnes.)
In the browser, you can use unpkg:
<script type="text/javascript" src="https://unpkg.com/jsnes/dist/jsnes.min.js"></script>// Initialize and set up outputs
var nes = new jsnes.NES({
onFrame: function(frameBuffer) {
// ... write frameBuffer to screen
},
onAudioSample: function(left, right) {
// ... play audio sample
}
});
// Read ROM data from disk (using Node.js APIs, for the sake of this example)
const fs = require('fs');
var romData = fs.readFileSync('path/to/rom.nes', {encoding: 'binary'});
// Load ROM data as a string or byte array
nes.loadROM(romData);
// Run frames at 60 fps, or as fast as you can.
// You are responsible for reliable timing as best you can on your platform.
nes.frame();
nes.frame();
// ...
// Hook up whatever input device you have to the controller.
nes.buttonDown(1, jsnes.Controller.BUTTON_A);
nes.frame();
nes.buttonUp(1, jsnes.Controller.BUTTON_A);
nes.frame();
// ...To build a distribution:
$ yarn run build
This will create dist/jsnes.min.js.
$ yarn test
You can use JSNES to embed a playable version of a ROM in a web page. This is handy if you are a homebrew ROM developer and want to put a playable version of your ROM on its web page. An example is in the example/ directory.
For a more complex example, see jsnes-web, a web UI written in React.
A potential improvement (hello contributors!) would be to make the React components in jsnes-web reusable so you could use them to embed a single ROM in a web page.
All code must conform to Prettier formatting. The test suite won't pass unless it does.
To automatically format all your code, run:
$ yarn run format
JSNES is based on James Sanders' vNES, and owes an awful lot to it. It also wouldn't have happened without Matt Wescott's JSSpeccy, which sparked the original idea. (Ben, circa 2008: "Hmm, I wonder what else could run in a browser?!")