Weird Array Pop() Behaviour

[Rink27]

I've been working on a plugin I created and noticed something odd.
The following is a representation of piece of my code:

var array = $gameVariables.value(x);
var array2 = $gameVariables.value(y); // x and y were given the same values

//EDIT: I meant x and y represent different numbers, but these game variables contain the same value.

var id = array.pop();
console.log("Array: "+$gameVariables.value(x));
console.log("Array: "+$gameVariables.value(y));

The arrays for BOTH game variables (x and y) are decreasing as I pop out values from "array".
Firstly, I thought only the new variable "array" would be affected, but $gameVariables.value(x) is also being affected.
Secondly, I don't understand why a different variable is also being affected.

I tested giving $gameVariables.value(y) a different array value and it was unaffected though. Does anyone recognise this issue?

 

[Poryg]

That's not weird at all. When x and y are given the same values, it means that x = y.
Therefore
$gameVariables.value(x) is the same as
$gameVariables.value(y)

and therefore since you pop one, you pop the other one as well.

As for why if you pop array, $gameVariables.value(x) also gets popped:

There are two major things to talk about: reference and value assignment.
Assignment happens when you either deal with immutable objects (numbers, letters) or with where you call the constructor function.
So you can freely say x = 3 and x = 5. Numbers are immutable, in other words 5 is always 5 and cannot be changed.
However, arrays are mutable. Therefore when you want to make a new one, you need to call a constructor function. There are multiple ways you create an array, one of them is via the new Array, but the most common is via these [] brackets.
When you do x = an already existing array, you reference the already existing array and therefore what influences the first one, influences the second one as well.

 

[Rink27]

That's not weird at all. When x and y are given the same values, it means that x = y.
Therefore
$gameVariables.value(x) is the same as
$gameVariables.value(y)

and therefore since you pop one, you pop the other one as well.

Thank you for the quick reply. I was wondering if it had to do with references - I'm familiar with the concept.
Um, one mistake on my part. When I said x and y were the same, I meant, for example:
$gameVariables.value(1) and $gameVariables.value(2) were both given the same values.
My bad; I didn't make that clear at all.

Is this behaviour still normal with my updated explanation?

 

[Poryg]

And how did you make the $gameVariables.value(1) and $gameVariables.value(2) arrays?

 

[Rink27]

And how did you make the $gameVariables.value(1) and $gameVariables.value(2) arrays?

A prior piece of code performs:
$gameVariables.setValue(1,theArray);
$gameVariables.setValue(2,theArray);

Edit: So I'm using the slice() method to clone the array, eliminating the need of the second variable ($gameVariables.value(2)) - I can preserve the array after popping it. Still curious where my understanding is flawed though with my updated explanation.

 

[Poryg]

And is theArray an already created array?
Like is it this format:

var theArray = [1,2,3];
$gameVariables.setValue(1, theArray);
$gameVariables.setValue(2, theArray);

if yes, it is reference, not assignment and therefore it would be normal.

 

[Rink27]

@Poryg

The code goes like:

var theArray = [];

// segment of code that pushes values into it

$gameVariables.setValue(1,theArray);
$gameVariables.setValue(2,theArray);

So I guess it's a reference still - thanks. I also edited my previous comment stating that I'm using the slice() method to solve my issue. Thanks for your time.

 

[Poryg]

Yup, slice method returns a new array, so that is completely fine. And that is the difference between reference and assignment.

 

[Kes]

[closed]IgnoreMe[/closed]