Javascript“这个”在 IE 中丢失上下文

发布于 2024-10-20 09:09:09 字数 803 浏览 2 评论 0原文

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]，这不是我想要的；当从handleEvent()输出时，“this”需要是对HandleClick对象的引用，而不是Window对象。

我是否遗漏了一些导致 IE 中出现此问题的基本内容？

<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>

原文

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.

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>

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听风吹 2024-10-27 09:09:09

.attachEvent() 不会为您提供 this 作为元素。您需要将处理程序包装在一个函数中，该函数从它所附加的元素的上下文中调用它。

    if( this.element.attachEvent ) {
        var that = this;
        this.element.attachEvent("onclick", function() { 
                                              that.handleEvent.call( that.element );
                                           } );
    }

.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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