利用eval给数组扩展表达式查询

Array.prototype.IndexOf = function (exp) {
            var isexp = exp.indexOf(‘=>‘) > -1, bef = isexp ? exp.split(‘=>‘)[0] : ‘‘, expstr = isexp ? exp.split(‘=>‘)[1].replace(new RegExp(bef, ‘g‘), ‘this[i].‘) : ‘‘;
            for (var i = 0; i < this.length; i++) {
                if (isexp && eval(expstr)) {
                    return i;
                } else {
                    if (this[i] == exp) {
                        return i;
                    }
                }
            }
            return -1;
        };