Javascript OOP inherits create GLOBAL object

Question

Look that.

// @alias ActiveRecord.extend
...
extend: function extend(destination, source){
   for (var property in source){
       destination[property] = source[property];
   }
   return destination;
}
...

I have this class:

function Exception(){}
Exception.prototype = {
    messages: {},
    add: function(k, v){
          if(!Array.isArray(this.messages[k])) this.messages[k] = new Array
          this.messages[k].push(v)
    }
}

And, i have this class. And it's call in method this.errors a new Exception.

function Validations(){
   this.errors = new Exception
}

And, i create this Model, the model have validations, the validations have errors, fine.

ActiveSupport.extend(Model.prototype, Validations.prototype)
function Model(){};

But... When I create a new instance a model and add errors to this instance, the Class Exception appears as a global object. LOOK...

a = new Model
a.errors.add('a', 1);
console.log(a.errors.messages) // return {a: [1]}

b = new Model
b.errors.add('a', 2);
console.log(b.errors.messages) // return {a: [1,2]}

How can I solve this?

How do I make the Array of messages of class Exception is not GLOBAL?

Answer 1

The problem lies in your Exception class:

function Exception(){}
Exception.prototype = {
    messages: {},
    add: function(k, v){
          if(!Array.isArray(this.m[k])) this.m[k] = new Array
          this.m[k].push(v)
          // did you mean this.messages ?
    }
}

I assume that this.m and this.messages are supposed to be the same thing, so i'll treat it as if that's how it is.

---

Your messages object is tied to the Exception prototype. This means that it's shared across all instances. It's now a very simple fix: Just put it in the initiation.

function Exception(){
    this.messages = {};
}
Exception.prototype = {
    add: function(k, v){
          if(!Array.isArray(this.m[k])) this.m[k] = new Array
          this.m[k].push(v)
          // did you mean this.messages ?
    }
}