jquery ready函数源代码研究_jquery

ready: function(fn) {
        // 绑定监听器
        bindReady();
        // 如果 DOM 加载完成
        if ( jQuery.isReady )
            // 马上运行此函数
            fn.call( document, jQuery );
        // 否则保存起来
        else
            // 把函数加入缓存数组中
            jQuery.readyList.push( function() { return fn.call(this, jQuery); } );
        return this;
}

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

// Mozilla,opera,webkitnightlies支持DOMContentLoaded事件
    if ( document.addEventListener && !jQuery.browser.opera)
        // 直接使用事件回调即可
        document.addEventListener( "DOMContentLoaded", jQuery.ready, false );

    // 如果是ie并且不是嵌在frame中
    // 就需要不断地检查文档是否加载完
    if ( jQuery.browser.msie && window == top ) (function(){
        if (jQuery.isReady) return;
        try {
            // 这个地方标记一下,在后面解析(1)
            document.documentElement.doScroll("left");
        } catch( error ) {
//// 这个地方标记一下,在后面解析(2)
            setTimeout( arguments.callee, 0 );
            return;
        }
        // and execute any waiting functions
        jQuery.ready();
    })();

    if ( jQuery.browser.opera )
        document.addEventListener( "DOMContentLoaded", function () {
            if (jQuery.isReady) return;
            for (var i = 0; i                 if (document.styleSheets[i].disabled) {
                    setTimeout( arguments.callee, 0 );
                    return;
                }
            // and execute any waiting functions
            jQuery.ready();
        }, false);

    if ( jQuery.browser.safari ) {
        var numStyles;
        (function(){
            if (jQuery.isReady) return;
            if ( document.readyState != "loaded" && document.readyState != "complete" ) { // 标记(4)
                setTimeout( arguments.callee, 0 );
                return;
            }
            if ( numStyles === undefined )
                numStyles = jQuery("style, link[rel=stylesheet]").length;
            if ( document.styleSheets.length != numStyles ) { // 标记(5)
                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 ); // 标记(6)
}
}