jquery中ready()函数执行的时机和window的load事件比较

// Handle when the DOM is ready
    ready: function() {
        // Make sure that the DOM is not already loaded
        if ( !jQuery.isReady ) {
            // Make sure body exists, at least, in case IE gets a little overzealous (ticket #5443).
            if ( !document.body ) {
                return setTimeout( jQuery.ready, 13 );
            }

            // Remember that the DOM is ready
            jQuery.isReady = true;

            // If there are functions bound, to execute
            if ( readyList ) {
                // Execute all of them
                var fn, i = 0;
                while ( (fn = readyList[ i++ ]) ) {
                    fn.call( document, jQuery );
                }

                // Reset the list of functions
                readyList = null;
            }

            // Trigger any bound ready events
            if ( jQuery.fn.triggerHandler ) {
                jQuery( document ).triggerHandler( "ready" );
            }
        }
    },