mass种子模块之domready

总结：由于IE6/7/8不支持DOMContentLoaded事件，虽然它支持onreadystatechange事件，但是readyState=complete几乎和onload事件一样，需要等页面中的外部资源加载完后才触发，想要尽快可采用doScroll检测法（仅在非iframe下有效）

 var turbo = turbo || {};
 var W3C = document.addEventListener ? true : false;
 var doc = document, html = document.documentElement;
 var readyList = [];
 turbo.ready = function(fn) {
     //不管是哪个分支，只要触发过一次ready事件readyList就会为null
     if (readyList) {
         readyList.push(fn);
     } else {
         fn();
     }
 };
 function fireReady() {
     if (readyList && readyList.length) {
         for (var i = 0, len = readyList.length; i < len; i++) {
             var fn = readyList[i];
             fn();
         }
     }
     readyList = null;
 }

 function doScrollCheck() {
     try {
         html.doScroll('left');
         fireReady();
     } catch (e) {
         setTimeout(doScrollCheck, 50);
     }
 }

 var ready = W3C ? "DOMContentLoaded" : "readystatechange";
 //由于firefox3.6不支持readyState，则在不支持readyState的时需手动赋值给它
 if (!doc.readyState) {
     //如果doc.body已存在则说明domcontentloaded了，将doc.readySate设置为complete
     var readyState = doc.readySate = doc.body ? "complete" : "loading";
 }

 if (doc.readyState == 'complete') {
     fireReady();
 } else {
     $.bind(doc, ready, function() {
         if (W3C || doc.readyState == 'complete') {
             fireReady();
             //firefox3.6,我觉得这里设不设置都行，因为这里已经用不到了doc.readyState了
             if (readyState) {
                 doc.readyState = 'complete';
             }
         }
     })
     //ie下使用doScroll，尽量提前触发ready，此方法只在非iframe下的页面有效
     var top = false;
     try {
         top = doc.frameElement == null && doc.documentElement;
     } catch (e) {}
     if (top && top.doScroll) {
         doScrollCheck();
     }
 }

有点看不懂mass里最后一段调用doScrollCheck的代码，故采用的jQuery的写法.