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;    };}

var arrList = [];if (arrList.indexOf(strID)== -1){     //做爱做的事                      }