Can I construct a JavaScript object without using the new keyword?

Question

Here is what I\'d like to do:

function a() {
  // ...
}
function b() {
  //  Some magic, return a new object.
}
var c = b();

c instanceof b // -> true
c          


        

Answer 1

Yes.

function _new(classConstructor, ...args) {
  var obj = Object.create(classConstructor.prototype);
  classConstructor.call(obj, ...args);
  return obj;
}

function test_new() {
  function TestClass(name, location) {
    this._name = name;
    this._location = location;
    this.getName = function() {
      return this._name;
    }
  }

  TestClass.prototype.getLocation = function() {
    return this._location;
  }
  TestClass.prototype.setName = function(newName) {
    this._name = newName;
  }

  const a = new TestClass('anil', 'hyderabad');
  const b = _new(TestClass, 'anil', 'hyderabad');

  const assert = console.assert
  assert(a instanceof TestClass)
  assert(b instanceof TestClass)
  assert(a.constructor.name === 'TestClass');
  assert(b.constructor.name === 'TestClass');
  assert(a.getName() === b.getName());
  assert(a.getLocation() === b.getLocation());
  a.setName('kumar');
  b.setName('kumar');
  assert(a.getName() === b.getName());
  console.log('All is well')
}
test_new()

Ref: https://gist.github.com/aniltallam/af358095bd6b36fa5d3dd773971f5fb7