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27 lines
991 B
27 lines
991 B
2 years ago
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'use strict';
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var $ = require('../internals/export');
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var uncurryThis = require('../internals/function-uncurry-this');
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var requireObjectCoercible = require('../internals/require-object-coercible');
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var toIntegerOrInfinity = require('../internals/to-integer-or-infinity');
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var toString = require('../internals/to-string');
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var fails = require('../internals/fails');
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var charAt = uncurryThis(''.charAt);
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var FORCED = fails(function () {
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// eslint-disable-next-line es-x/no-array-string-prototype-at -- safe
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return '𠮷'.at(-2) !== '\uD842';
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});
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// `String.prototype.at` method
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// https://github.com/tc39/proposal-relative-indexing-method
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$({ target: 'String', proto: true, forced: FORCED }, {
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at: function at(index) {
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var S = toString(requireObjectCoercible(this));
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var len = S.length;
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var relativeIndex = toIntegerOrInfinity(index);
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var k = relativeIndex >= 0 ? relativeIndex : len + relativeIndex;
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return (k < 0 || k >= len) ? undefined : charAt(S, k);
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}
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});
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