core-js/internals/array-species-create.js

var isObject = require('../internals/is-object');
var isArray = require('../internals/is-array');
var wellKnownSymbol = require('../internals/well-known-symbol');

var SPECIES = wellKnownSymbol('species');

// `ArraySpeciesCreate` abstract operation
// https://tc39.github.io/ecma262/#sec-arrayspeciescreate
module.exports = function (originalArray, length) {
  var C;
  if (isArray(originalArray)) {
    C = originalArray.constructor;
    // cross-realm fallback
    if (typeof C == 'function' && (C === Array || isArray(C.prototype))) C = undefined;
    else if (isObject(C)) {
      C = C[SPECIES];
      if (C === null) C = undefined;
    }
  } return new (C === undefined ? Array : C)(length === 0 ? 0 : length);
};