使用JS异步回调解决pjax加载问题

 function loadScript(src, callback) {
  var script = document.createElement('script'),
head = document.getElementsByTagName('head')[0];
script.type = 'text/javascript';
script.charset = 'UTF-8';
script.src = src;
if (script.addEventListener) {
  script.addEventListener('load', function () {
      callback();
    }, false);
  } else if (script.attachEvent) {
    script.attachEvent('onreadystatechange', function () {
        var target = window.event.srcElement;
        if (target.readyState == 'loaded') {
          callback();
        }
      });
    }
    head.appendChild(script);
  }