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JavaScript Object-Oriented JavaScript (2015) Constructor Functions and Prototypes Adding a Prototype

`Monster.prototype.takeDamage` is not a function

Getting this whether I have the new property declared or not, even when the method is still on the constructor and the starter code is untouched. Code for the prototype addition:

Monster.prototype.takeDamage = function() { this.health--; };

monster.js
var Monster = function(name) {
  this.name = name;
  this.health = 100;
  this.takeDamage = function() {
    this.health -= 1;

  }
};

2 Answers

Bruno Navarrete
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Bruno Navarrete
Full Stack JavaScript Techdegree Graduate 22,246 Points

This code should be after your prototype declaration (var Monster...):

Monster.prototype.takeDamage = function() {
    this.health -= 1;
}

You'll also have to remove this.takeDamage from the prototype.

Bruno, thanks. I swear that's exactly how I had it and it wasn't working before but now it is. I think I might have been leaving out "prototype" from the property assignment in my original code. Either that or it's those damn JavaScript gremlins! :-)

Anyway this works as it should:

function Monster( name ) {
  this.name = name;
  this.health = 100;

}

Monster.prototype.takeDamage = function() {
  this.health--;

};