what-happens.js

function A() {
  this.test = function() {
    console.log('A:test');
  };
}

class B extends A {
  test() {
    console.log('B:test"1');
    super.test()
  }
  test = function() {
    console.log('B:test"2');
    super.test()
  }
}

(new B()).test()