javascript inheritance by prototype

Question

I was reading this article, and I took the example and made some very small modification

function Parent( p1, p2 ) {
  console.log('run here');
  var prop1 = p1;       // private property
  this.prop2 = p2;  // public property
  // private method
  function meth1() { return prop1; }
  // public methods
  this.meth2 = function(){ return this.prop2; };
  this.meth6 = function(){ return meth1(); };
}
Parent.prototype.hello=function(){console.log('hi '+this.prop2);};



function Child( p1, p2, p3, p4 ) {
        Parent.apply( this, arguments ); // initialize Parent's members
        this.prop3 = p3;
        this.meth3 = function(){ return this.prop3; };  // override
        var prop4 = p4;
        this.meth4 = function(){ return prop4; };
    }
Child.prototype = new Parent(); // set up inheritance relation
// console.log(Child.prototype)
var cc = new Child( "one", "two", "three", "four" );
console.log(cc)

var result1 = cc.meth6();       // parent property via child
var result2 = cc.meth2();   // parent method via child
var result3 = cc.meth3();   // child method overrides parent method
var result4 = cc.hello();   
console.log(result1,result2,result3,result4);

The problem is even cc.hello method seems like exist, but when I call it, the console return undefined, can someone please explain why? thanks

The hello method doesn't return anything, thus undefined. Not sure what you expect... — elclanrs
– elclanrs, Commented Aug 13, 2015 at 22:17

Starfish · Accepted Answer · 2015-08-13 22:18:17Z

1

The method hello doesn't return a value, thus it is undefined

You can change the method to something like this to return the value:

Parent.prototype.hello = function(){
  return 'hi '+ this.prop2;
};

answered Aug 13, 2015 at 22:18

Starfish

3,6541 gold badge25 silver badges58 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Sean H Over a year ago

Hahaha, thanks, I guess my brain was short circuited :P

Collectives™ on Stack Overflow

javascript inheritance by prototype

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related