jQuery(document).ready多久会被调用？

如果第三方javascript文件挂起并需要一段时间加载,将会

jQuery(document).ready(function() {}) 

在被叫之前必须等待加载？

是的,它必须等待.特别是,jQuery(document).ready()在其他脚本有机会执行之前,您不能依赖于触发. ready绑定到DOMContentReady,readystatechanged或onload,无论哪个可用.

该文档指出"在大多数情况下,脚本可以在DOM层次结构完全构建后立即运行".请注意,唯一的保证是在此事件触发时DOM已准备就绪. 它不能保证你的任何其他东西 - 因为它不能.

这一点,例如不会在IE,Firefox或铬工作,brilliant.js是一直呼吁的前ready()处理程序有机会执行不管你怎么洗牌脚本标记:

仅供参考,这是jquery-1.4.2的相关代码:

bindReady: function() {
    if ( readyBound ) {
        return;
    }

    readyBound = true;

    // Catch cases where $(document).ready() is called after the
    // browser event has already occurred.
    if ( document.readyState === "complete" ) {
        return jQuery.ready();
    }

    // Mozilla, Opera and webkit nightlies currently support this event
    if ( document.addEventListener ) {
        // Use the handy event callback
        document.addEventListener( "DOMContentLoaded", DOMContentLoaded, false );

        // A fallback to window.onload, that will always work
        window.addEventListener( "load", 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", DOMContentLoaded);

        // A fallback to window.onload, that will always work
        window.attachEvent( "onload", jQuery.ready );

        // If IE and not a frame
        // continually check to see if the document is ready
        var toplevel = false;

        try {
            toplevel = window.frameElement == null;
        } catch(e) {}

        if ( document.documentElement.doScroll && toplevel ) {
            doScrollCheck();
        }
    }
},