/*

终于解决了IE8不支持数组的indexOf方法

*/

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;

    };

}