ie7,IE8不支持document.getElmentsByClassName的问题

 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;
     };
 }

解决ie7,IE8不支持document.getElmentsByClassName的问题