怎么样判断页面是否加载完成

 

           if (document.readyState == "complete") {
                   //加载完后运行的js代码                }
                else {
                    document.onreadystatechange = function() {
                        if (document.readyState == "complete") {
                            //加载完后运行的js代码 
                        }
                    }
                }