Spawn

event-driven web workers for modern browsers

Download

• JS

• spawn.js big, or
• spawn.min.js small

Install

<script src="https://cdn.rawgit.com/kevinjamesus86/spawn/v1.1.0/dist/spawn.js"></script>
or
<script src="https://cdn.rawgit.com/kevinjamesus86/spawn/v1.1.0/dist/spawn.min.js"></script>

Usage

Function as the source

// create a worker with a
// function as the source
var worker = Spawn(
  function workerThreadSource() {

    // it could take time..
    function fib(num) {
      if (num < 2) {
        return num;
      } else {
        return fib(num - 1) + fib(num - 2);
      }
    }

    // listen for the `fib` event
    spawn.on('fib', function(val, send) {

      // send the result back to the emitter
      send( fib(val) );
    });

  }
);

// emit an event and send some data to the worker
worker.emit('fib', 42, function(result) {

  // the *async* result of our workers labor
  console.log('the fib of 42 is:', result);

  // close if/when you're done with it
  this.close();
});

File as the source

fib.js

// it could take time..
function fib(num) {
  if (num < 2) {
    return num;
  } else {
    return fib(num - 1) + fib(num - 2);
  }
}

// listen for the `fib` event
spawn.on('fib', function(val, send) {

  // send the result back to the emitter
  send( fib(val) );
});

app.js

// create the worker
var worker = Spawn('fib.js');

// emit an event and send some data to the worker
worker.emit('fib', 42, function(result) {

  // the *async* result of our workers labor
  console.log('the fib of 42 is:', result);

  // close if/when you're done with it
  this.close();
});

API

Spawn(source: {Function|string} [, config: Object])

Spawns a new worker from a function or file path. Functions passed as the source will be unwrapped and executed in the workers global scope. File paths passed as the source will be imported and executed in the workers global scope.

Config

Option	Default	Description
workerAs	spawn	A workers default Spawn instance name. This can also be set globally at Spawn.config.workerAs

Default config

var maths = Spawn(
  function mathsSource() {

    // Round a value towards zero
    spawn.on('fix', function fix(num, send) {
      send( num > 0 ? Math.floor(num) : Math.ceil(num) );
    });

  }
);

Your config

// Could also be set globally with
// Spawn.config.workerAs = 'mathsWorker'

var maths = Spawn(
  function mathsSource() {

    // Round a value towards zero
    mathsWorker.on('fix', function fix(num, send) {
      send( num > 0 ? Math.floor(num) : Math.ceil(num) );
    });

  }, {
    workerAs: 'mathsWorker'
  }
);

• on(event: string, handler: Function(data: any, send: Function))

  Adds an event handler for a given event. The handler function receives two arguments: data passed from the emitter, and a function for sending data back to the emitter.

• emit(event: string [, data: any][, callback: Function(data: any)])

  Triggers an event passing on data to the listeners. The callback function receives one argument: data sent from the event listener that was triggered by the emitted event.

  // Emit an event from the worker thread,
  // listening for the event on the main thread
  
  Spawn(function() {
  
    spawn.emit('open', 'yap');
  
  }).on('open', function(msg) {
    console.log('Worker is ready, and says "' + msg + '"');
    this.close();
  });
  
  // Emit an event from the main thread,
  // listening for the event on the worker thread
  
  Spawn(function() {
  
    spawn.on('reverse', function(str, send) {
      send( str.split('').reverse().join('') );
    });
  
  }).emit('reverse', 'racecar', function(val) {
    console.log('"racecar" backwards is "' + val + '"');
    this.close();
  });

• close()

  Discards any tasks queued in the worker's event loop, effectively closing the worker.

• importScripts(script: string [, ...])

  Imports one or more scripts into the worker's global scope. importScripts supports absolute paths, relative paths, URLs, and object URLs.

  anyhex.js from Paul Irish

  function anyHex() {
    return '#' + Math.floor(Math.random() * 16777215).toString(16);
  }

  app.js

  Spawn(function {
    // load it
    spawn.importScripts('anyhex.js');
  
    spawn.on('anyhex', function(_, send) {
      send( anyHex() );
    });
  });

  or

  var worker = Spawn(function {
    spawn.on('anyhex', function(_, send) {
      send( anyHex() );
    });
  });
  // load it
  worker.importScripts('anyhex.js');