indexOf.js

// from http://qiita.com/Oakbow/items/3374175d76d82792134d
(function () {

    if (!("indexOf" in Array.prototype)) {
        Array.prototype.indexOf = function (find, i) {
            var n;
            if (i === undefined) i = 0;
            if (i < 0) i += this.length;
            if (i < 0) i = 0;
            n = this.length;
            while (i < n) {
                if (i in this && this[i] === find) return i;
                i++;
            }
            return -1;
        };
    }

}).call(this);