Having trouble understanding references in JavaScript

Question

I am a little bit confused about how referencing works in JavaScript so I would appreciate it if someone could help me out on this one:
```javascript
var myName = "Gabriel";
var yourName = myName
console.log(yourName) //This prints out "Gabriel" as expected
yourName = "Harry"
console.log(yourName) //This prints out "Harry" as expected
console.log(myName) //This prints out "Gabriel" as expected
```
Up until this point it does what I expect from the code, but this is where the confusion begins.
Problem 1:
```javascript
var Harry = {
    age: 32
};
var Mary = Harry;
Mary.age = 20;
console.log(Harry.age) //This prints out 20 instead of 32
```
And it doesn't end here.
Problem 2:
```javascript
var arrayOne = [0,1,2,3];
var arrayTwo = [4,5,6,7];
arrayTwo = arrayOne
console.log(arrayTwo) //This prints out [0,1,2,3] as expected
arrayTwo[0] = 5;
console.log(arrayTwo) //This prints out [5,1,2,3] as expected
console.log(arrayOne) //But this also prints out [5,1,2,3] instead of [0,1,2,3]
```
So why are these things happening? I read it that it has something to do with references, but still couldn't find any clear answer. Can anyone explain it to me? Or is there a place where I can find a good material on this subject?

Jonathan Grieve · Answer

The thing with problem one is it looks like you're making Harry take on the properties of Mary, rather than having them exist as 2 separate objects
```javascript
var Harry = {
    age: 32
};
var Mary{
 age = 20;
}
console.log(Harry.age); 
console.log(Mary.age);
```
Again with problem 2 i think what's happening is you're overrrding one array so it takes on the values of another.  So instead of having 2 arrays with the different values, both references will now show the same values. Even when you make an edit to one array index.  
That's how I understand it, hope it helps  :)

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Gabriel D. Celery

Gabriel D. Celery

Having trouble understanding references in JavaScript

1 Answer

Jonathan Grieve

Jonathan Grieve