progressive shim to defer execution until next run-loop cycle

JavaScript: nextTick.js

/**
 * progressive shim to defer execution until next run-loop cycle
 *
 * prefers
 * - `process.nextTick` over
 * - `process.setImmediate` or `window.setImmediate` over
 * - `window.requestAnimationFrame` over
 * - `window.postMessage` and `window.addEventListener` over
 * - `setTimeout` as the very last resort
 */

ns = {};

ns.nextTick = (function (root) {
  "use strict";
  
  var owner = typeof process === "undefined" ? root : process,
      vendorPrefixes = "webkitR-mozR-msR-oR-r".split("-"),
      suffix = "equestAnimationFrame",
      nextTick = owner.nextTick || owner.setImmediate,
      queue;

  while (!nextTick && vendorPrefixes.length){
    nextTick = owner[vendorPrefixes.pop() + suffix];
  }

  if (!nextTick && root.postMessage && root.addEventListener){
    queue = [];

    root.addEventListener('message', function(evt){
      var source = evt.source;

      if ((source == root || source == null) && evt.data === 'nextTick'){
        evt.stopPropagation();
        if (queue.length) queue.shift()();
      }
    }, true);

    return function(func){
      queue.push(func);
      root.postMessage('nextTick', '*');
    };
  }

  nextTick = nextTick || setTimeout;

  return function (){
    return nextTick.apply(owner, arguments);
  };
}(this));

/**
 * minified version ~0.5kb:
 
 nextTick=function(c){for(var b="undefined"===typeof process?c:process,e=["webkitR","mozR","msR","oR","r"],a=b.a||b.setImmediate,d;!a&&e.length;)a=b[e.pop()+"equestAnimationFrame"];!a&&c.postMessage&&c.addEventListener&&(d=[],c.addEventListener("message",function(a){var b=a.source;b!=c&&null!=b||"nextTick"!==a.data||(a.stopPropagation(),d.length&&d.shift()())},!0),a=function(a){d.push(a);c.postMessage("nextTick","_")});a=a||setTimeout;return function(){return a.apply(b,arguments)}}(this);

 */