_array-species-constructor.js

var isObject = require('./_is-object');
var isArray = require('./_is-array');
var SPECIES = require('./_wks')('species');

module.exports = function (original) {
  var C;
  if (isArray(original)) {
    C = original.constructor;
    // cross-realm fallback
    if (typeof C == 'function' && (C === Array || isArray(C.prototype))) C = undefined;
    if (isObject(C)) {
      C = C[SPECIES];
      if (C === null) C = undefined;
    }
  } return C === undefined ? Array : C;
};