https://www.hec.gov.pk/Style%20Library/HEC/js/polyfill.js

1if (!Array.prototype.includes) {
2  Object.defineProperty(Array.prototype, 'includes', {
3    value: function (searchElement, fromIndex) {
4 
5      if (this == null) {
6        throw new TypeError('"this" is null or not defined');
7      }
8 
9      // 1. Let O be ? ToObject(this value).
10      var o = Object(this);
11 
12      // 2. Let len be ? ToLength(? Get(O, "length")).
13      var len = o.length >>> 0;
14 
15      // 3. If len is 0, return false.
16      if (len === 0) {
17        return false;
18      }
19 
20      // 4. Let n be ? ToInteger(fromIndex).
21      //    (If fromIndex is undefined, this step produces the value 0.)
22      var n = fromIndex | 0;
23 
24      // 5. If n ≥ 0, then
25      //  a. Let k be n.
26      // 6. Else n < 0,
27      //  a. Let k be len + n.
28      //  b. If k < 0, let k be 0.
29      var k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);
30 
31      function sameValueZero(x, y) {
32        return x === y || (typeof x === 'number' && typeof y === 'number' && isNaN(x) && isNaN(y));
33      }
34 
35      // 7. Repeat, while k < len
36      while (k < len) {
37        // a. Let elementK be the result of ? Get(O, ! ToString(k)).
38        // b. If SameValueZero(searchElement, elementK) is true, return true.
39        if (sameValueZero(o[k], searchElement)) {
40          return true;
41        }
42        // c. Increase k by 1. 
43        k++;
44      }
45 
46      // 8. Return false
47      return false;
48    }
49  });
50}