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