javascript处理事件的一些兼容写法

绑定事件

var addEvent = function( obj, type, fn ) { 
    if (obj.addEventListener) 
        obj.addEventListener( type, fn, false ); 
    else if (obj.attachEvent) { 
        obj["e"+type+fn] = fn; 
        obj.attachEvent( "on"+type, function() { 
            obj["e"+type+fn](); 
        } ); 
    } 
};

另一个实现

var addEvent = (function () {  
    if (document.addEventListener) {  
        return function (el, type, fn) {  
            el.addEventListener(type, fn, false);  
        };  
    } else {  
        return function (el, type, fn) {  
            el.attachEvent('on' + type, function () {  
                return fn.call(el, window.event);  
            });  
        }  
    }  
})();

移除事件

var removeEvent = function(obj, type, fn) { 
    if (obj.removeEventListener) 
        obj.removeEventListener( type, fn, false ); 
    else if (obj.detachEvent) { 
        obj.detachEvent( "on"+type, obj["e"+type+fn] ); 
        obj["e"+type+fn] = null; 
    } 
}

加载事件与脚本

var loadEvent = function(func) { 
    var oldonload = window.onload; 
    if (typeof window.onload != 'function') { 
        window.onload = func; 
    }else { 
        window.onload = function() { 
            oldonload(); 
            func(); 
        } 
    } 
}

阻止事件

var cancelEvent = function(event) { 
    event = event||window.event 
    if (event.preventDefault) { 
        event.preventDefault(  ); 
        event.stopPropagation(  ); 
    } else { 
        event.returnValue = false; 
        event.cancelBubble = true; 
    } 
}

取得事件源对象

相当于Prototype.js框架的Event.element(e)

var getTarget = function(event){ 
    event = event || window.event; 
    var obj = event.srcElement ? event.srcElement : event.target; 
    return obj 