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https://github.com/bfirsh/jsnes

A JavaScript NES emulator.
https://github.com/bfirsh/jsnes

6502 emulation emulator javascript nes

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A JavaScript NES emulator.

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# JSNES



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](https://github.com/bfirsh/jsnes-web).



## Installation



For Node.js or Webpack:



    $ npm install jsnes



(Or `yarn add jsnes`.)



In the browser, you can use [unpkg](https://unpkg.com):



```html



```



## Usage



```javascript

// 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();

// ...

```



## Build



To build a distribution:



    $ yarn run build



This will create `dist/jsnes.min.js`.



## Running tests



    $ yarn test



## Embedding JSNES in a web page



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.



The best implementation is [jsnes-web](https://github.com/bfirsh/jsnes-web) but unfortunately it is not trivial to reuse the code. You'll have to copy and paste the code from that repository, the use the [``](https://github.com/bfirsh/jsnes-web/blob/master/src/Emulator.js) React component. [Here is a usage example.](https://github.com/bfirsh/jsnes-web/blob/d3c35eec11986412626cbd08668dbac700e08751/src/RunPage.js#L119-L125).



A project for potential contributors (hello!): jsnes-web should be reusable and on NPM! It just needs compiling and bundling.



A more basic example is in the `example/` directory of this repository. Unfortunately this is known to be flawed, and doesn't do timing and sound as well as jsnes-web.



## Formatting code



All code must conform to [Prettier](https://prettier.io/) formatting. The test suite won't pass unless it does.



To automatically format all your code, run:



    $ yarn run format



## Maintainers



- [Ben Firshman](http://github.com/bfirsh)

- [Ben Jones](https://github.com/BenShelton)

- [Stephen Hicks](https://github.com/shicks)

- [Alison Saia](https://github.com/allie)



JSNES is based on [James Sanders' vNES](https://github.com/bfirsh/vNES), and owes an awful lot to it. It also wouldn't have happened without [Matt Wescott's JSSpeccy](http://jsspeccy.zxdemo.org/), which sparked the original idea. (Ben, circa 2008: "Hmm, I wonder what else could run in a browser?!")