49 lines
1.3 KiB
JavaScript
49 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
|
|
};
|
|
};
|