38 lines
1.4 KiB
JavaScript
38 lines
1.4 KiB
JavaScript
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'use strict';
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var uncurryThis = require('../internals/function-uncurry-this');
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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 requireObjectCoercible = require('../internals/require-object-coercible');
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var charAt = uncurryThis(''.charAt);
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var charCodeAt = uncurryThis(''.charCodeAt);
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var stringSlice = uncurryThis(''.slice);
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var createMethod = function (CONVERT_TO_STRING) {
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return function ($this, pos) {
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var S = toString(requireObjectCoercible($this));
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var position = toIntegerOrInfinity(pos);
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var size = S.length;
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var first, second;
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if (position < 0 || position >= size) return CONVERT_TO_STRING ? '' : undefined;
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first = charCodeAt(S, position);
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return first < 0xD800 || first > 0xDBFF || position + 1 === size
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|| (second = charCodeAt(S, position + 1)) < 0xDC00 || second > 0xDFFF
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? CONVERT_TO_STRING
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? charAt(S, position)
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: first
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: CONVERT_TO_STRING
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? stringSlice(S, position, position + 2)
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: (first - 0xD800 << 10) + (second - 0xDC00) + 0x10000;
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};
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};
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module.exports = {
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// `String.prototype.codePointAt` method
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// https://tc39.es/ecma262/#sec-string.prototype.codepointat
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codeAt: createMethod(false),
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// `String.prototype.at` method
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// https://github.com/mathiasbynens/String.prototype.at
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charAt: createMethod(true)
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};
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