.indexOf() not working in IE8

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Why doesn't indexOf work on an array IE8? 7 answers

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When you take a look at MDN's Array.indexOf Article, You will see that

indexOf is a recent addition to the ECMA-262 standard; as such it may not be present in all browsers. You can work around this by utilizing the following code at the beginning of your scripts. This will allow you to use indexOf when there is still no native support. This algorithm matches the one specified in ECMA-262, 5th edition, assuming Object, TypeError, Number, Math.floor, Math.abs, and Math.max have their original values.

if (!Array.prototype.indexOf) {
    Array.prototype.indexOf = function (searchElement /*, fromIndex */ ) {
        "use strict";
        if (this == null) {
            throw new TypeError();
        }
        var t = Object(this);
        var len = t.length >>> 0;
        if (len === 0) {
            return -1;
        }
        var n = 0;
        if (arguments.length > 1) {
            n = Number(arguments[1]);
            if (n != n) { // shortcut for verifying if it's NaN
                n = 0;
            } else if (n != 0 && n != Infinity && n != -Infinity) {
                n = (n > 0 || -1) * Math.floor(Math.abs(n));
            }
        }
        if (n >= len) {
            return -1;
        }
        var k = n >= 0 ? n : Math.max(len - Math.abs(n), 0);
        for (; k < len; k++) {
            if (k in t && t[k] === searchElement) {
                return k;
            }
        }
        return -1;
    }
}

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