core-js/src/immediate.js

Standard library

// setImmediate shim
// Node.js 0.9+ & IE10+ has setImmediate, else:
isFunction(setImmediate) && isFunction(clearImmediate) || function(ONREADYSTATECHANGE){
  var postMessage      = global.postMessage
    , addEventListener = global.addEventListener
    , MessageChannel   = global.MessageChannel
    , counter          = 0
    , queue            = {}
    , defer, channel, port;
  setImmediate = function(fn){
    var args = [], i = 1;
    while(arguments.length > i)args.push(arguments[i++]);
    queue[++counter] = function(){
      invoke(isFunction(fn) ? fn : Function(fn), args);
    }
    defer(counter);
    return counter;
  }
  clearImmediate = function(id){
    delete queue[id];
  }
  function run(id){
    if(has(queue, id)){
      var fn = queue[id];
      delete queue[id];
      fn();
    }
  }
  function listner(event){
    run(event.data);
  }
  // Node.js 0.8-
  if(NODE){
    defer = function(id){
      nextTick(part.call(run, id));
    }
  // Modern browsers, skip implementation for WebWorkers
  // IE8 has postMessage, but it's sync & typeof its postMessage is object
  } else if(addEventListener && isFunction(postMessage) && !global.importScripts){
    defer = function(id){
      postMessage(id, '*');
    }
    addEventListener('message', listner, false);
  // WebWorkers
  } else if(isFunction(MessageChannel)){
    channel = new MessageChannel;
    port    = channel.port2;
    channel.port1.onmessage = listner;
    defer = ctx(port.postMessage, port, 1);
  // IE8-
  } else if(document && ONREADYSTATECHANGE in document[CREATE_ELEMENT]('script')){
    defer = function(id){
      html.appendChild(document[CREATE_ELEMENT]('script'))[ONREADYSTATECHANGE] = function(){
        html.removeChild(this);
        run(id);
      }
    }
  // Rest old browsers
  } else {
    defer = function(id){
      setTimeout(part.call(run, id), 0);
    }
  }
}('onreadystatechange');
$define(GLOBAL + BIND, {
  setImmediate:   setImmediate,
  clearImmediate: clearImmediate
});