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46 lines
1.3 KiB
46 lines
1.3 KiB
'use strict'; |
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var $TypeError = require('es-errors/type'); |
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var isNegativeZero = require('math-intrinsics/isNegativeZero'); |
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var isObject = require('es-object-atoms/isObject'); |
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var callBound = require('call-bound'); |
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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 isPropertyKey = require('../helpers/isPropertyKey'); |
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var isInteger = require('math-intrinsics/isInteger'); |
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// https://262.ecma-international.org/12.0/#sec-stringgetownproperty |
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module.exports = function StringGetOwnProperty(S, P) { |
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var str; |
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if (isObject(S)) { |
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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 (typeof 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: P is not a Property Key'); |
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} |
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if (typeof 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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