$(document).ready 相当于没有 jQuery [英] $(document).ready equivalent without jQuery

问题描述

我有一个使用 $(document).ready 的脚本，但它没有使用 jQuery 中的任何其他内容.我想通过删除 jQuery 依赖来减轻它的负担.

I have a script that uses $(document).ready, but it doesn't use anything else from jQuery. I'd like to lighten it up by removing the jQuery dependency.

如何在不使用 jQuery 的情况下实现我自己的 $(document).ready 功能?我知道使用 window.onload 会有所不同，因为 window.onload 在加载所有图像、帧等后触发.

How can I implement my own $(document).ready functionality without using jQuery? I know that using window.onload will not be the same, as window.onload fires after all images, frames, etc. have been loaded.

推荐答案

有一个基于标准的替换，DOMContentLoaded 被超过 99% 的浏览器，虽然不是 IE8:

There is a standards based replacement,DOMContentLoaded that is supported by over 99% of browsers, though not IE8:

document.addEventListener("DOMContentLoaded", function(event) { 
  //do work
});

jQuery 的原生函数比 window.onload 复杂得多，如下所示.

jQuery's native function is much more complicated than just window.onload, as depicted below.

function bindReady(){
    if ( readyBound ) return;
    readyBound = true;

    // Mozilla, Opera and webkit nightlies currently support this event
    if ( document.addEventListener ) {
        // Use the handy event callback
        document.addEventListener( "DOMContentLoaded", function(){
            document.removeEventListener( "DOMContentLoaded", arguments.callee, false );
            jQuery.ready();
        }, false );

    // If IE event model is used
    } else if ( document.attachEvent ) {
        // ensure firing before onload,
        // maybe late but safe also for iframes
        document.attachEvent("onreadystatechange", function(){
            if ( document.readyState === "complete" ) {
                document.detachEvent( "onreadystatechange", arguments.callee );
                jQuery.ready();
            }
        });

        // If IE and not an iframe
        // continually check to see if the document is ready
        if ( document.documentElement.doScroll && window == window.top ) (function(){
            if ( jQuery.isReady ) return;

            try {
                // If IE is used, use the trick by Diego Perini
                // http://javascript.nwbox.com/IEContentLoaded/
                document.documentElement.doScroll("left");
            } catch( error ) {
                setTimeout( arguments.callee, 0 );
                return;
            }

            // and execute any waiting functions
            jQuery.ready();
        })();
    }

    // A fallback to window.onload, that will always work
    jQuery.event.add( window, "load", jQuery.ready );
}

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