Call an overridden method in base class constructor in typescript

Question

When I'm calling an overridden method from the base class constructor, I cannot get a value of a sub class property correctly.

Example:

class A {     constructor()     {         this.MyvirtualMethod();     }      protected MyvirtualMethod(): void     {      } }  class B extends A {     private testString: string = "Test String";      public MyvirtualMethod(): void     {         alert(this.testString); // This becomes undefined     } } 

I would like to know how to correctly override functions in typescript.

Answer 1

The key is calling the parent's method using super.methodName();

class A {     // A protected method     protected doStuff()     {         alert("Called from A");     }      // Expose the protected method as a public function     public callDoStuff()     {         this.doStuff();     } }  class B extends A {      // Override the protected method     protected doStuff()     {         // If we want we can still explicitly call the initial method         super.doStuff();         alert("Called from B");     } }  var a = new A(); a.callDoStuff(); // Will only alert "Called from A"  var b = new B() b.callDoStuff(); // Will alert "Called from A" then "Called from B" 

Try it here