Member Attribute undefined in Member Methods of Javascript Object

Asked Dec 09 '15 at 11:07

Active Dec 09 '15 at 11:07

Viewed 30 times

I'm trying to use Object-Oriented Javascript, following the model shown in the MDN Tutorial here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Introduction_to_Object-Oriented_JavaScript#Prototype-based_programming

So I have my constructor:

// Constructor
var Transmitters = function() {

    this.tdb = new Array();
    this.arrNearbyList = new Array('asfd');

};

Then I try to access it in a member method:

// Load into the member attribute
Transmitters.prototype.parseTransmitters = function(transmitterData) {

    this.tdb = transmitterData;

    this.arrNearbyList.push("test"); 

};

I get TypeError: this.arrNearbyList is undefined. If I try to access this.tdb from another member method it's also undefined, so it's only local in scope to the parseTransmitters method.

I'm pretty sure I followed the way it's shown in the MDN article, I don't understand what I'm doing wrong here.

asked Dec 09 '15 at 11:07

David Findlay

2

It all depends on how you're *calling* `parseTransmitters`. – T.J. Crowder Dec 09 '15 at 11:08
1

Probably a duplicate of: http://stackoverflow.com/questions/3127429/how-does-the-this-keyword-work – T.J. Crowder Dec 09 '15 at 11:09
I'm using var objNearbyTransmitters = new Transmitters(); objNearbyTransmitters.parseTransmitters(); – David Findlay Dec 09 '15 at 11:09
1

`this` depends on how you are calling `parseTransmitters()` – Ramanlfc Dec 09 '15 at 11:11
1

@DavidFindlay: If you were, you wouldn't be getting that error, not with the code above: http://jsfiddle.net/4datzm6k/ – T.J. Crowder Dec 09 '15 at 11:15
Ok I'll have to look in case it's being called somewhere else I'm not expecting it to be. That's definitely how I'm intending to call it. – David Findlay Dec 09 '15 at 11:17

Member Attribute undefined in Member Methods of Javascript Object

0 Answers0