Javascript“这个"在 IE 中丢失上下文 [英] Javascript "this" losing context in IE
问题描述
以下在 firefox/safari/chrome 中工作正常，在 IE 中，this"似乎在 handleEvent() 函数中丢失上下文...警报的结果是 [object Window]，这不是我的想;当 handleEvent() 输出时，this"需要是对 HandleClick 对象的引用，而不是 Window 对象.
The following works fine in firefox/safari/chrome, in IE, "this" appears to be losing context in the handleEvent() function...the result of the alert is [object Window], which is not what I want; when output from handleEvent(), "this" needs to be a reference to the HandleClick object, not the Window object.
我是否遗漏了导致 IE 出现这种情况的一些基本内容?
Am I missing something basic which is causing this in IE?
<html>
<head>
<script type="text/javascript">
HandleClick = function(el) {
this.element = document.getElementById(el);
if( this.element.addEventListener ) {
this.element.addEventListener("click", this, false);
} else {
if( this.element.attachEvent ) {
this.element.attachEvent("onclick", this.handleEvent);
}
}
}
HandleClick.prototype = {
handleEvent: function(e) {
alert(this);
}
}
</script>
</head>
<body onload="new HandleClick('logo')"></body>
</html>
推荐答案
.attachEvent() 没有给你 this 作为元素.您需要将处理程序包装在一个函数中，该函数从它所附加到的元素的上下文中调用它.
.attachEvent() doesn't give you this as the element. You'd need to wrap the handler in a function that invokes it from the context of the element to which it is attached.
if( this.element.attachEvent ) {
var that = this;
this.element.attachEvent("onclick", function() {
that.handleEvent.call( that.element );
} );
}
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