监听浏览器使用不同版本js并且处理ie兼容getElementByClassName

if(window.addEventListener){    document.write(‘<script src="js/jquery-2.1.4.min.js"><\/script>‘);

}else if(window.attachEvent){    document.write(‘<script src="js/jquery-1.8.3.min.js"><\/script>‘);    //解决ie兼容getElementByClassName    if(!document.getElementsByClassName){        document.getElementsByClassName = function(className, element){            var children = (element || document).getElementsByTagName(‘*‘);            var elements = new Array();            for (var i=0; i<children.length; i++){                var child = children[i];                var classNames = child.className.split(‘ ‘);                for (var j=0; j<classNames.length; j++){                    if (classNames[j] == className){                        elements.push(child);                        break;                    }                }            }

            return elements;        };    }    //

}else{    document.write(‘<script src="js/jquery-2.1.4.min.js"><\/script>‘);}