function addEvent(obj,type,fn){    if(obj.addEventListener){        obj.addEventListener(type,fn,false);    }else if(obj.attachEvent){        obj.attachEvent(‘on‘+type,function(){            fn.call(this);        });    }}function removeEvent(obj,type,fn){    if(obj.removeEventListener){        obj.removeEventListener(type,fn,false);    }else if(obj.detachEvent){        obj.detachEvent(‘on‘+type,fn);    }}function preDef(evt){    var e = evt || window.event;    if(e.preventDefault){        e.preventDefault();    }else{        e.returnValue = false;    }}//跨浏览器获取目标对象function getTarget(evt){    if(evt.target){        return evt.target;    }else if(window.event.srcElement){        return window.event.srcElement;    }}//跨浏览器获取字符编码function getCharCode(evt){    var e = evt || window.event;    if(typeof e.charCode == ‘number‘){        return e.charCode;    }else{        return e.keyCode;    }}