js中ie8下不识别indexOf的解决办法

把一下代码放在你的indexOf方法的上面：

if (!Array.prototype.indexOf){
          Array.prototype.indexOf = function(elt /*, from*/){
        var len = this.length >>> 0;
        var from = Number(arguments[1]) || 0;
        from = (from < 0)
             ? Math.ceil(from)
             : Math.floor(from);
        if (from < 0)
          from += len;
        for (; from < len; from++)
        {
          if (from in this &&
              this[from] === elt)
            return from;
        }
        return -1;
      };
    }