动态加载脚本和样式

1. 动态加载js文件

var flag = False;

if(flag) {

var script = document.createElement("script");

script.type = "text/javascript";

script.src = "browserdetect.js";

var head = document.getElementsByTagName("head")[0];

head.appendChild(script);

}   //这段代码不放在onload里面

2. 动态加载javascript代码

var flag = False;

if(flag) {

var script = document.createElement("script");

script.type = "text/javascript";

script.text =  "alert('lee')";

var head = document.getElementsByTagName("head")[0];

head.appendChild(script);

}  

3. 动态样式

var link= document.createElement("link");

link.rel = "stylesheet";

link.type = "text/css";

link.href = "basic.css";

var head = document.getElementsByTagName("head")[0];

head.appendChild(link);

4. 动态执行样式

var flag = False;

if(flag) {

var link= document.createElement("link");

link.type = "text/css";

doucment.styleSheets[0].addRule();  //使用styleSheet添加动态样式

var head = document.getElementsByTagName("head")[0];

head.appendChild(link);

}