1 window.onload = function() 2 { 3 var al = document.getElementsByTagName("script"); 4 var new_element=document.createElement("script");  5 var joine = [] 6 for(var i = 0; i<al.length; i++) 7 { 8     joine.push(al[i].getAttribute("src")); 9 }10 var ajoine = joine.join(",");11 console.log(ajoine);12 if(IndexDemo(ajoine,‘jquery.min.js‘)>0)13     {14         console.log(‘1‘);15         //alert(1);16     }else{17         console.log(‘2‘);18         var new_element=document.createElement("script"); 19         new_element.setAttribute("type","text/javascript"); 20         new_element.setAttribute("src","/static/js/jquery-1.5.1/jquery.min.js");// 在这里引入了a.js 21         document.body.appendChild(new_element); 22         //alert(2);23     }24 }25 26 function IndexDemo(str1,str2){27    var list = str128    var s = list.indexOf(str2);29    return(s);30 }