source: frontend/node_modules/es-abstract/2015/StringGetIndexProperty.js

'use strict';

var callBound = require('call-bound');

var $TypeError = require('es-errors/type');

var $charAt = callBound('String.prototype.charAt');

var isString = require('is-string');
var isNegativeZero = require('math-intrinsics/isNegativeZero');
var unbox = require('unbox-primitive');

var CanonicalNumericIndexString = require('./CanonicalNumericIndexString');
var IsInteger = require('./IsInteger');
var isPropertyKey = require('../helpers/isPropertyKey');

// https://262.ecma-international.org/6.0/#sec-stringgetindexproperty

module.exports = function StringGetIndexProperty(S, P) {
        if (typeof S === 'string' || !isString(S)) {
                throw new $TypeError('Assertion failed: `S` must be a boxed String Object');
        }
        if (!isPropertyKey(P)) {
                throw new $TypeError('Assertion failed: `P` must be a Property Key');
        }

        if (typeof P !== 'string') {
                return void undefined;
        }

        var index = CanonicalNumericIndexString(P);
        if (typeof index === 'undefined' || !IsInteger(index) || isNegativeZero(index)) {
                return void undefined;
        }

        var str = unbox(S);
        var len = str.length;
        if (index < 0 || len <= index) {
                return void undefined;
        }

        var resultStr = $charAt(str, index);

        return {
                '[[Configurable]]': false,
                '[[Enumerable]]': true,
                '[[Value]]': resultStr,
                '[[Writable]]': false
        };
};