jquery的ready()实现的是 DOMContentLoaded 事件，DOMContentLoaded与window load事件的区别
简单的说ready()是在文档加载完成就会触发,此时图片等资源可能还没有完全加载, load是在所有资源都加载完成后才会触发
看下ready函数的代码就什么都清楚了。下面的代码加上了注释：
// 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" ); } } },