--- /dev/null
+var ctx = require('./_ctx')
+ , invoke = require('./_invoke')
+ , html = require('./_html')
+ , cel = require('./_dom-create')
+ , global = require('./_global')
+ , process = global.process
+ , setTask = global.setImmediate
+ , clearTask = global.clearImmediate
+ , MessageChannel = global.MessageChannel
+ , counter = 0
+ , queue = {}
+ , ONREADYSTATECHANGE = 'onreadystatechange'
+ , defer, channel, port;
+var run = function(){
+ var id = +this;
+ if(queue.hasOwnProperty(id)){
+ var fn = queue[id];
+ delete queue[id];
+ fn();
+ }
+};
+var listener = function(event){
+ run.call(event.data);
+};
+// Node.js 0.9+ & IE10+ has setImmediate, otherwise:
+if(!setTask || !clearTask){
+ setTask = function setImmediate(fn){
+ var args = [], i = 1;
+ while(arguments.length > i)args.push(arguments[i++]);
+ queue[++counter] = function(){
+ invoke(typeof fn == 'function' ? fn : Function(fn), args);
+ };
+ defer(counter);
+ return counter;
+ };
+ clearTask = function clearImmediate(id){
+ delete queue[id];
+ };
+ // Node.js 0.8-
+ if(require('./_cof')(process) == 'process'){
+ defer = function(id){
+ process.nextTick(ctx(run, id, 1));
+ };
+ // Browsers with MessageChannel, includes WebWorkers
+ } else if(MessageChannel){
+ channel = new MessageChannel;
+ port = channel.port2;
+ channel.port1.onmessage = listener;
+ defer = ctx(port.postMessage, port, 1);
+ // Browsers with postMessage, skip WebWorkers
+ // IE8 has postMessage, but it's sync & typeof its postMessage is 'object'
+ } else if(global.addEventListener && typeof postMessage == 'function' && !global.importScripts){
+ defer = function(id){
+ global.postMessage(id + '', '*');
+ };
+ global.addEventListener('message', listener, false);
+ // IE8-
+ } else if(ONREADYSTATECHANGE in cel('script')){
+ defer = function(id){
+ html.appendChild(cel('script'))[ONREADYSTATECHANGE] = function(){
+ html.removeChild(this);
+ run.call(id);
+ };
+ };
+ // Rest old browsers
+ } else {
+ defer = function(id){
+ setTimeout(ctx(run, id, 1), 0);
+ };
+ }
+}
+module.exports = {
+ set: setTask,
+ clear: clearTask
+};
\ No newline at end of file