es.string.at-alternative.js
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es.string.at-alternative.js
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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/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);
			}
			});