LoadScript jquery

+function(){
  var oldScript = document.getElementsByTagName('script');
  var body = document.getElementsByTagName('body')[0];
  var script = document.createElement('script');
  script.onload = function(){
    console.log("jquery load");
  }
  script.src = 'http://code.jquery.com/jquery-2.2.4.js';

  //Object.prototype.toString.call(script)  HTMLCollection集合无法使用forEach
  for(var i=0; i<oldScript.length; i++){
    if(oldScript[i].src.indexOf('jquery') != -1){
      oldScript[i].remove();
    }
  }
  body.appendChild(script)

}()