$( document ).ready()

最新推荐文章于 2023-12-07 21:59:32 发布

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本文介绍了jQuery中如何使用$(document).ready()和$(window).load()来确保DOM及整个页面加载完成后才运行JavaScript代码。通过示例展示了两种方法的区别，并提供了一段HTML和JavaScript结合的代码实例。

A page can't be manipulated safely until the document is "ready." jQuery detects this state of readiness for you. Code included inside $( document ).ready() will only run once the page Document Object Model (DOM) is ready for JavaScript code to execute. Code included inside $( window ).load(function() { ... }) will run once the entire page (images or iframes), not just the DOM, is ready.

// A $( document ).ready() block.
$( document ).ready(function() {
    console.log( "ready!" );
});

Experienced developers sometimes use the shorthand $() for $( document ).ready(). If you are writing code that people who aren't experienced with jQuery may see, it's best to use the long form.

// Shorthand for $( document ).ready()
$(function() {
    console.log( "ready!" );
});

You can also pass a named function to $( document ).ready() instead of passing an anonymous function.

// Passing a named function instead of an anonymous function.
 
function readyFn( jQuery ) {
    // Code to run when the document is ready.
}
 
$( document ).ready( readyFn );
// or:
$( window ).load( readyFn );

The example below shows $( document ).ready() and $( window ).load() in action. The code tries to load a website URL in an <iframe> and checks for both events:

<html>
<head>
    <script src="https://code.jquery.com/jquery-1.9.1.min.js"></script>
    <script>
    $( document ).ready(function() {
        console.log( "document loaded" );
    });
 
    $( window ).load(function() {
        console.log( "window loaded" );
    });
    </script>
</head>
<body>
    <iframe src="http://techcrunch.com"></iframe>
</body>
</html>