为什么window.onload工作而document.onload不工作？
[英]Why does window.onload work while document.onload doesn't?
问题描述
Can anyone tell me why the following page doesn't trigger an alert when it loads? 
任何人都可以告诉我为什么下一页加载时不会触发警报？ If I use window.onload instead of document.onload it works. 如果我使用window.onload而不是document.onload它可以工作。 Why is there this difference? 为什么会出现这种差异？
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
document.onload = function() {
alert('Test');
}
</script>
</head>
<body>
</body>
</html>
2 个解决方案
解决方案1
8 已采纳 2011-02-27 20:28:49
The simplest answer is that it just wasn't designed that way. 最简单的答案是它不是那样设计的。 The browser executes the function attached to window.onload at the " end of the document loading process ". 浏览器在“ 文档加载过程结束时 ”执行附加到window.onload的功能。 It does not attempt to execute a function attached to document.onload . 它不会尝试执行附加到document.onload的函数。
You could assign a function to document.onload but the browser will not do anything special with it. 您可以为document.onload分配一个函数，但浏览器不会对它做任何特殊操作。
Some things to keep in mind (assuming you've just assigned a function to one or the other of window.onload or document.onload ): 要注意的一些事项（假设您刚刚为window.onload或document.onload一个或另一个分配了一个函数）：
-
window.onload === onload -
window.onload !== document.onload -
window !== document
解决方案2
1 2011-02-27 20:18:21
The event handler is onload not document.onload . 事件处理程序是onload而不是document.onload 。 It hangs directly off the window object (which is the default object). 它直接挂在window对象（这是默认对象）之外。
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