事件模块的演变（6）

基于“勿重复判断浏览器”的原则，将添加/删除/触发事件的三个分支重写。如下

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var w3c = !!window.addEventListener,       addListener = w3c ?         function(el, type, fn) { el.addEventListener(type, fn, false); } :         function(el, type, fn) { el.attachEvent('on' + type, fn); },               removeListener = w3c ?         function(el, type, fn) { el.removeEventListener(type, fn, false); } :         function(el, type, fn) { el.detachEvent('on' + type, fn); };           dispatch = w3c ?         function(el, type){             try{                 var evt = document.createEvent('Event');                 evt.initEvent(type,true,true);                 el.dispatchEvent(evt);             }catch(e){alert(e)};         } :         function(el, type){             try{                 el.fireEvent('on'+type);             }catch(e){alert(e)}         };

接口改为了on/un/fire

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return {     on : add,     un : remove,     fire : dispatch };

event-0.3.js