30 lines
658 B
JavaScript
30 lines
658 B
JavaScript
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Array.prototype.includes = function(searchElement /*, fromIndex*/) {
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'use strict';
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if (this == null) {
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throw new TypeError('Array.prototype.includes called on null or undefined');
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}
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var O = Object(this);
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var len = parseInt(O.length, 10) || 0;
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if (len === 0) {
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return false;
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}
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var n = parseInt(arguments[1], 10) || 0;
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var k;
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if (n >= 0) {
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k = n;
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} else {
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k = len + n;
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if (k < 0) {k = 0;}
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}
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var currentElement;
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while (k < len) {
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currentElement = O[k];
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if (searchElement === currentElement ||
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(searchElement !== searchElement && currentElement !== currentElement)) { // NaN !== NaN
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return true;
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}
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k++;
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}
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return false;
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};
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