JavaScript异步加载方案

Answer 1

function loadScript(url, callback){
   var script = document.createElement("script")
   script.type = "text/javascript";
   if (script.readyState){ //IE
      script.onreadystatechange = function(){
         if (script.readyState == "loaded" || script.readyState == "complete"){
            script.onreadystatechange = null;
            callback();
         }
      };
   } else { //Others: Firefox, Safari, Chrome, and Opera
      script.onload = function(){
          callback();
      };
   }
   script.src = url;
   document.body.appendChild(script);
}