1. 页面中直接引用
<script src="a.js"><\/script> <script src="b.js"><\/script>
document.write('<script src="a.js"><\/script>')
document.write('<script src="b.js"><\/script>')
function include(path){ 
var a=document.createElement("script"); 
a.type = "text/javascript"; 
a.src=path; 
var head=document.getElementsByTagName("head")[0]; 
head.appendChild(a); 
} 
include("a.js")
include("b.js")
require.js的方法