Javascript - adding function to prototype results in TypeError

Question

I am trying to add a function to the BattleState object.
I am using the prototype method as I don't want the function to be serialised, as described in Use of 'prototype' vs. 'this' in JavaScript?

This is roughly how I have my code set up, when I call the getPlayerStateFromBattleState function, I get an error saying "TypeError: Cannot find default value for object." I assume it is the function that I've added to the prototype that can't be found, but I may be wrong. Does anyone know what is causing this?

function BattleState() {
  this.player1 = new PlayerState();
  this.player1.id = 1;
  this.player2 = new PlayerState();
  this.player2.id = 2;
};


BattleState.prototype.getPlayerStateFromBattleState = function(thisPlayerId) {
  if (this.player1.id == thisPlayerId) {
    return this.player1;
  } else if (this.player2.id == thisPlayerId) {
    return this.player2;
  } else {
    // Error
  }
}


var battleState = new BattleState();

// This line resutls in "TypeError: Cannot find default value for object."
var playerState = battleState.getPlayerStateFromBattleState(1);

What line of code is associated with that error? If the code you posted is only "roughly" the code with which you're experiencing problems, get rid of it and post the *actual* code. This stuff here looks fine. — Pointy, Dec 21 '15 at 14:18
Do you use Rhino? http://stackoverflow.com/questions/14561874/calling-jsfunction-from-javascript-typeerror-cannot-find-default-value-for-ob — Tamas Hegedus, Dec 21 '15 at 14:21

score 0 · Accepted Answer · answered Dec 21 '15 at 14:35

0

I tried to reproduce the problem:

// This line resutls in "TypeError: Cannot find default value for object."
console.log(battleState.getPlayerStateFromBattleState(2));

https://jsfiddle.net/kg85w55e/

The given code just worked. I think there is something in your PlayerState Class. Could you Adjust your question and include your PlayerState Class?

answered Dec 21 '15 at 14:35

Max Sassen

650
5
15

You're right, the problem is in the PlayerState, thanks! – user5703660 Dec 21 '15 at 16:41

Javascript - adding function to prototype results in TypeError

1 Answers1