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48 lines
1.3 KiB
48 lines
1.3 KiB
'use strict'; |
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var GetIntrinsic = require('get-intrinsic'); |
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var $TypeError = GetIntrinsic('%TypeError%'); |
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var callBound = require('call-bind/callBound'); |
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var $charAt = callBound('String.prototype.charAt'); |
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var $stringToString = callBound('String.prototype.toString'); |
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var CanonicalNumericIndexString = require('./CanonicalNumericIndexString'); |
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var IsInteger = require('./IsInteger'); |
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var IsPropertyKey = require('./IsPropertyKey'); |
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var Type = require('./Type'); |
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var isNegativeZero = require('is-negative-zero'); |
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// https://262.ecma-international.org/8.0/#sec-stringgetownproperty |
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module.exports = function StringGetOwnProperty(S, P) { |
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var str; |
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if (Type(S) === 'Object') { |
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try { |
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str = $stringToString(S); |
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} catch (e) { /**/ } |
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} |
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if (Type(str) !== 'String') { |
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throw new $TypeError('Assertion failed: `S` must be a boxed string object'); |
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} |
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if (!IsPropertyKey(P)) { |
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throw new $TypeError('Assertion failed: IsPropertyKey(P) is not true'); |
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} |
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if (Type(P) !== 'String') { |
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return void undefined; |
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} |
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var index = CanonicalNumericIndexString(P); |
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var len = str.length; |
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if (typeof index === 'undefined' || !IsInteger(index) || isNegativeZero(index) || index < 0 || len <= index) { |
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return void undefined; |
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} |
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var resultStr = $charAt(S, index); |
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return { |
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'[[Configurable]]': false, |
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'[[Enumerable]]': true, |
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'[[Value]]': resultStr, |
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'[[Writable]]': false |
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}; |
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};
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