一个浏览器渲染和操作的顺序如下：

1、HTML解析完毕；

2、外部脚本和样式表加载完成；

3、脚本爱文档内解析并执行；

4、HTML DOM完全构造起来；

5、图片和外部内容加载。

由此顺序下来，当dom加载完毕前就执行对应的dom操作势必会出问题，原来我们中文站的search suggest的错误就在于此。对于的一些方法：

第一种，最常见最简单的做法，等待页面完全加载完毕后触发。也就是绑定window对象的onload事件。：

window.onload=function(){

 //相应操作；

}

第二种，因为在页面中途嵌入的含内脚本可以访问该位置之前的DOM,所以可以变通地在页面最底部添加脚本来执行。

第三中，写一个函数自己判断Dom的加载

function domReady( f ) {
    // If the DOM is already loaded, execute the function right away
    if ( domReady.done ) return f();

    // If we’ve already added a function
    if ( domReady.timer ) {
        // Add it to the list of functions to execute
        domReady.ready.push( f  );
    } else {
        // Attach an event for when the page finishes  loading,
        // just in case it finishes first. Uses addEvent.
        addEvent( window, “load”, isDOMReady );

        // Initialize the array of functions to execute
        domReady.ready = [ f ];

        //  Check to see if the DOM is ready as quickly as possible
        domReady.timer = setInterval( isDOMReady, 13 );
    }
}

// Checks to see if the DOM is ready for navigation
function isDOMReady() {
    // If we already figured out that the page is ready, ignore
    if ( domReady.done ) return false;

    // Check to see if a number of functions and elements are
    // able to be accessed
    if ( document && document.getElementsByTagName && 
          document.getElementById && document.body ) {

        // If they’re ready, we can stop checking
        clearInterval( domReady.timer );
        domReady.timer = null;

        // Execute all the functions that were waiting
        for ( var i = 0; i < domReady.ready.length; i++ )
            domReady.ready[i]();

        // Remember that we’re now done
        domReady.ready = null;
        domReady.done = true;
    }
}

function domReady( f ) {<br/> // If the DOM is already loaded, execute the function right away<br/> if ( domReady.done ) return f();<br/><br/> // If we’ve already added a function<br/> if ( domReady.timer ) {<br/> // Add it to the list of functions to execute<br/> domReady.ready.push( f );<br/> } else {<br/> // Attach an event for when the page finishes loading,<br/> // just in case it finishes first. Uses addEvent.<br/> addEvent( window, “load”, isDOMReady );<br/><br/> // Initialize the array of functions to execute<br/> domReady.ready = [ f ];<br/><br/> // Check to see if the DOM is ready as quickly as possible<br/> domReady.timer = setInterval( isDOMReady, 13 );<br/> }<br/>}<br/><br/>// Checks to see if the DOM is ready for navigation<br/>function isDOMReady() {<br/> // If we already figured out that the page is ready, ignore<br/> if ( domReady.done ) return false;<br/><br/> // Check to see if a number of functions and elements are<br/> // able to be accessed<br/> if ( document && document.getElementsByTagName && <br/> document.getElementById && document.body ) {<br/><br/> // If they’re ready, we can stop checking<br/> clearInterval( domReady.timer );<br/> domReady.timer = null;<br/><br/> // Execute all the functions that were waiting<br/> for ( var i = 0; i < domReady.ready.length; i++ )<br/> domReady.ready[i]();<br/><br/> // Remember that we’re now done<br/> domReady.ready = null;<br/> domReady.done = true;<br/> }<br/>}<br/>

ps:很佩服老外，会为了这么点速度上的先后去写专门的函数。想想国内会有多少公司去这么做