1 function loadJs(jssrc, callback) { 2         if (jssrc) { 3             var head = document.getElementsByTagName(‘head‘)[0]; 4             var script = document.createElement(‘script‘); 5             if (script.readyState) { //IE 6                 script.onreadystatechange = function () { 7                     if (script.readyState == "loaded" || script.readyState == "complete") { 8                         script.onreadystatechange = null; 9                         if (callback && typeof callback == ‘function‘) {10                             callback();11                         }12                     }13                 };14             } else { //Others15                 script.onload = function () {16                     if (callback && typeof callback == ‘function‘) {17                         callback();18                     }19                 }20             }21             script.src =http://www.mamicode.com/ jssrc;22             head.appendChild(script);23         }24     }