Calling function from parent class in child instance [javascript]

I need to call functions from a parent class via the instances of the child class.

class A {   function A1()    function A2()   function A3()   } class B extends A {   function B1()     function B2() }  const X = new B(); X.A1();

Above is a sample pseudocode.

How should I go about this? Any help is appreciated.

Thanks in advance!