Asynchronous constructor

Question

How can I best handle a situation like the following?

I have a constructor that takes a while to complete.

var Element = function Element(name){
            


        

Answer 1

I extract out the async portions into a fluent method. By convention I call them together.

class FooBar {
  constructor() {
    this.foo = "foo";
  }
  
  async create() {
    this.bar = await bar();

    return this;
  }
}

async function bar() {
  return "bar";
}

async function main() {
  const foobar = await new FooBar().create(); // two-part constructor
  console.log(foobar.foo, foobar.bar);
}

main(); // foo bar

I tried a static factory approach wrapping new FooBar(), e.g. FooBar.create(), but it didn't play well with inheritance. If you extend FooBar into FooBarChild, FooBarChild.create() will still return a FooBar. Whereas with my approach new FooBarChild().create() will return a FooBarChild and it's easy to setup an inheritance chain with create().