// Copyright 2020 the V8 project authors. All rights reserved.// Use of this source code is governed by a BSD-style license that can be// found in the LICENSE file.namespace string {// https://tc39.es/proposal-item-method/#sec-string.prototype.attransitioning javascript builtin StringPrototypeAt( js-implicit context: NativeContext, receiver: JSAny)(index: JSAny): JSAny { // 1. Let O be ? RequireObjectCoercible(this value). // 2. Let S be ? ToString(O). const s = ToThisString(receiver, 'String.prototype.at'); // 3. Let len be the length of S. const len = s.length_smi; // 4. Let relativeIndex be ? ToInteger(index). const relativeIndex = ToInteger_Inline(index); // 5. If relativeIndex ≥ 0, then // a. Let k be relativeIndex. // 6. Else, // a. Let k be len + relativeIndex. const k = relativeIndex >= 0 ? relativeIndex : len + relativeIndex; // 7. If k < 0 or k ≥ len, then return undefined. if (k < 0 || k >= len) { return Undefined; } // 8. Return the String value consisting of only the code unit at position k // in S. return StringFromSingleCharCode(StringCharCodeAt(s, Convert<uintptr>(k)));}}