Strict mode Passingnon-Strict mode Passing
Features:
- Symbol.species
// Copyright (C) 2020 Alexey Shvayka. All rights reserved. // This code is governed by the BSD license found in the LICENSE file. /*--- esid: sec-array.prototype.flatmap description: > Non-writable properties are overwritten by CreateDataProperty. (result object's "0" is non-writable, source array is not flattened) info: | Array.prototype.flatMap ( mapperFunction [ , thisArg ] ) [...] 6. Perform ? FlattenIntoArray(A, O, sourceLen, 0, depthNum). FlattenIntoArray ( target, source, sourceLen, start, depth [ , mapperFunction, thisArg ] ) [...] 9. Repeat, while sourceIndex < sourceLen [...] c. If exists is true, then [...] v. If shouldFlatten is true, then [...] vi. Else, [...] 2. Perform ? CreateDataPropertyOrThrow(target, ! ToString(targetIndex), element). [...] features: [Symbol.species] includes: [propertyHelper.js] ---*/ var A = function(_length) { Object.defineProperty(this, "0", { value: 1, writable: false, enumerable: false, configurable: true, }); }; var arr = [2]; arr.constructor = {}; arr.constructor[Symbol.species] = A; var res = arr.flatMap(function(item) { return item; }); verifyProperty(res, "0", { value: 2, writable: true, enumerable: true, configurable: true, });