how to call parent constructor?

Question

Let\'s say I have the following code snippet.

function test(id) { alert(id); }

testChild.prototype = new test();

function testChild(){}

var instance = new         


        

Answer 1

You already have many answers, but I'll throw in the ES6 way, which IMHO is the new standard way to do this.

class Parent { 
  constructor() { alert('hi'); } 
}
class Child extends Parent { 
  // Optionally include a constructor definition here. Leaving it 
  // out means the parent constructor is automatically invoked.
  constructor() {
    // imagine doing some custom stuff for this derived class
    super();  // explicitly call parent constructor.
  }
}

// Instantiate one:
var foo = new Child();  // alert: hi