// Array.indexOf polyfill for IE8
if (!Array.prototype.indexOf) {
    Array.prototype.indexOf = function (searchElement, fromIndex) {
        var k;

        // 1. Let O be the result of calling ToObject passing
        //    the this value as the argument.
        if (this == null) {
            throw new TypeError('"this" is null or not defined');
        }

        var O = Object(this);

        // 2. Let lenValue be the result of calling the Get
        //    internal method of O with the argument "length".
        // 3. Let len be ToUint32(lenValue).
        var len = O.length >>> 0;

        // 4. If len is 0, return -1.
        if (len === 0) {
            return -1;
        }

        // 5. If argument fromIndex was passed let n be
        //    ToInteger(fromIndex); else let n be 0.
        var n = +fromIndex || 0;

        if (Math.abs(n) === Infinity) {
            n = 0;
        }

        // 6. If n >= len, return -1.
        if (n >= len) {
            return -1;
        }

        // 7. If n >= 0, then Let k be n.
        // 8. Else, n<0, Let k be len - abs(n).
        //    If k is less than 0, then let k be 0.
        k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);

        // 9. Repeat, while k < len
        while (k < len) {
            // a. Let Pk be ToString(k).
            //   This is implicit for LHS operands of the in operator
            // b. Let kPresent be the result of calling the
            //    HasProperty internal method of O with argument Pk.
            //   This step can be combined with c
            // c. If kPresent is true, then
            //    i.  Let elementK be the result of calling the Get
            //        internal method of O with the argument ToString(k).
            //   ii.  Let same be the result of applying the
            //        Strict Equality Comparison Algorithm to
            //        searchElement and elementK.
            //  iii.  If same is true, return k.
            if (k in O && O[k] === searchElement) {
                return k;
            }
            k++;
        }
        return -1;
    };
}