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- 'use strict';
- var $TypeError = require('es-errors/type');
- var callBound = require('call-bind/callBound');
- var $charAt = callBound('String.prototype.charAt');
- var $stringToString = callBound('String.prototype.toString');
- var CanonicalNumericIndexString = require('./CanonicalNumericIndexString');
- var IsIntegralNumber = require('./IsIntegralNumber');
- var IsPropertyKey = require('./IsPropertyKey');
- var Type = require('./Type');
- var isNegativeZero = require('is-negative-zero');
- // https://262.ecma-international.org/12.0/#sec-stringgetownproperty
- module.exports = function StringGetOwnProperty(S, P) {
- var str;
- if (Type(S) === 'Object') {
- try {
- str = $stringToString(S);
- } catch (e) { /**/ }
- }
- if (typeof str !== 'string') {
- throw new $TypeError('Assertion failed: `S` must be a boxed string object');
- }
- if (!IsPropertyKey(P)) {
- throw new $TypeError('Assertion failed: IsPropertyKey(P) is not true');
- }
- if (typeof P !== 'string') {
- return void undefined;
- }
- var index = CanonicalNumericIndexString(P);
- var len = str.length;
- if (typeof index === 'undefined' || !IsIntegralNumber(index) || isNegativeZero(index) || index < 0 || len <= index) {
- return void undefined;
- }
- var resultStr = $charAt(S, index);
- return {
- '[[Configurable]]': false,
- '[[Enumerable]]': true,
- '[[Value]]': resultStr,
- '[[Writable]]': false
- };
- };
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