js文件中调用js的实现方法

//引入util.js文件
var head = document.head || document.getElementsByTagName('head')[0];
var new_js=document.createElement("script");
new_js.setAttribute("type","text/javascript");
new_js.setAttribute("src","/p/servjs/util.js");
head.appendChild(new_js);

document.write(" <script language=\"javascript\" src=\"/p/servjs/util.js\" > <\/script>"); 

$("head").append("<script language=\"javascript\" src=\"\/p\/servjs\/util.js\" > <\/script>");