What is it called when a function creates new objects but doesn't use the class keyword, nor "new" keyword (in JavaScript)?

Question

I can’t seem to find the term for a function that acts like a class constructor – in that it creates new objects of a certain “shape” – but doesn't use the new keyword, nor class. (Is it a constructor function? It doesn’t have that keyword either!)

I've used both this pattern and classes in my code but realized I don't know how to describe the former.

An example of this idiom:

const makeCounter = () => {
  let val = 0;
  
  return { 
    increment() { val++; }, 
    getVal() { return val; },
  };
};

let aCounter = makeCounter();

aCounter.increment();
aCounter.increment();
console.log(aCounter.getVal());      //= 2

What should makeCounter be called?

Answer 1

It's called a "factory function".

Factory functions usually return a object of a consistent type but are not instances of the factory function itself. Returned objects would rarely inherit from the factory function's prototype property, and calling the factory function does not require new before the function called.