do errors thrown in initialisers cause an abrupt completion of construction?

[michaelficarra]

class A {
  b = (_ => { throw 0; })();
  c = f();
  constructor() {
    g();
  }
}

Is f() evaluated? Is g()? Does new A throw? If not, what is the value of new A().b?

[fatfisz]

f() will be evaluated when new A() is executed. The same for g(). new A should throw when b's initializer is executed.

Amirite?

[jeffmo]

new A will throw and neither f(), nor the constructor() method itself will be evaluated here.

[michaelficarra]

So new A is guaranteed to evaluate the initialiser of b before the initialiser of c and before the constructor body?

[jeffmo]

Yes: https://github.com/jeffmo/es-class-static-properties-and-fields#instance-field-initialization-process

intended to run once for each field in the order they are declared