userAgentInfo.indexOf(Agents[v]):
//A.indexOf(array[i]):A元素是否存在于数组array里面;如果存在就会返回对应的下标,如果不存在则返回-1.
function IsPC(){
 var userAgentInfo = navigator.userAgent;//使用navigator.userAgent来判断浏览器类型。  
var Agents = new Array("Android", "iPhone", "SymbianOS", "Windows Phone", "iPad", "iPod");  
 var flag = true;
    for (var v = 0; v < Agents.length; v++) {
       if (userAgentInfo.indexOf(Agents[v]) >= 0) {
       flag = false;
       break;
       }
    }
   return flag;
}
A.indexOf(array[i])表达的含义
原文:http://www.cnblogs.com/lxl0419/p/5738410.html