Constnium/node_modules/es-abstract/2018/StringGetOwnProperty.js
2022-06-23 02:27:43 +02:00

48 lines
1.3 KiB
JavaScript

'use strict';
var GetIntrinsic = require('get-intrinsic');
var $TypeError = GetIntrinsic('%TypeError%');
var callBound = require('call-bind/callBound');
var $charAt = callBound('String.prototype.charAt');
var $stringToString = callBound('String.prototype.toString');
var CanonicalNumericIndexString = require('./CanonicalNumericIndexString');
var IsInteger = require('./IsInteger');
var IsPropertyKey = require('./IsPropertyKey');
var Type = require('./Type');
var isNegativeZero = require('is-negative-zero');
// https://262.ecma-international.org/8.0/#sec-stringgetownproperty
module.exports = function StringGetOwnProperty(S, P) {
var str;
if (Type(S) === 'Object') {
try {
str = $stringToString(S);
} catch (e) { /**/ }
}
if (Type(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 (Type(P) !== 'String') {
return void undefined;
}
var index = CanonicalNumericIndexString(P);
var len = str.length;
if (typeof index === 'undefined' || !IsInteger(index) || isNegativeZero(index) || index < 0 || len <= index) {
return void undefined;
}
var resultStr = $charAt(S, index);
return {
'[[Configurable]]': false,
'[[Enumerable]]': true,
'[[Value]]': resultStr,
'[[Writable]]': false
};
};