Last change
on this file since b738035 was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago |
initial commit
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1 | // TODO: disabled by default because of the conflict with another proposal
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2 | 'use strict';
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3 | var $ = require('../internals/export');
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4 | var requireObjectCoercible = require('../internals/require-object-coercible');
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5 | var toInteger = require('../internals/to-integer');
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6 | var toLength = require('../internals/to-length');
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7 | var toString = require('../internals/to-string');
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8 | var fails = require('../internals/fails');
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9 |
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10 | var FORCED = fails(function () {
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11 | return '𠮷'.at(0) !== '\uD842';
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12 | });
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13 |
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14 | // `String.prototype.at` method
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15 | // https://github.com/tc39/proposal-relative-indexing-method
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16 | $({ target: 'String', proto: true, forced: FORCED }, {
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17 | at: function at(index) {
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18 | var S = toString(requireObjectCoercible(this));
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19 | var len = toLength(S.length);
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20 | var relativeIndex = toInteger(index);
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21 | var k = relativeIndex >= 0 ? relativeIndex : len + relativeIndex;
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22 | return (k < 0 || k >= len) ? undefined : S.charAt(k);
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23 | }
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24 | });
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