You have to update variables if it contains another variable that has been modified??

Question

I just wanna be clear.
If you have this:
javascript
var candyAmt = 10;
var yum = "I have " + candyAmt + " pieces of skittles";

and the variable candyAmt is modified
javascript
candyAmt -= 2;

you have to define any variable (that you continue to use) containing candyAmt, again??
javascript
yum = "I have " + candyAmt + " pieces of skittles.";
var response = "Dion gave away 2 skittles and said, \"Now, " + yum + "\"" ;

Is that right?? Variables won't update itself within another variable, just as standalone?

Ignazio Calo · Accepted Answer

I see your question, and the answer is "no" the other variable is not auto-updated.
To put this concept in a better way, the moment when you write:
javascript
var yum = "I have " + candyAmt + " pieces of skittles";

a variable called yum is defined, the the computer looks at the right part of the assignment and start building that string, taking I have, then checking the current value of the variable candyAmt and appending to the first part, and at the end appending pieces of skittles.
When the whole expression is completed, the result is finally inserted into the yum.
At that point there is not information anymore that the string was built using the candyAmt variable. It's just a string.
In other words, if you have:
javascript
var total = 100 + 100

The sum is calculated only once and the value is stored into the total variable, is not re-evaluated every time.

Ignazio Calo · Answer

yep the first one is 180, the second one 160.
A more clean way to obtain the same result is do not use a variable, but use a function instead.
```javascript
var num = 10;
var total = function(param) {
    return param * 2
};
console.log(total(num)); //20
num += 10
console.log(total(num)); //40
num += 10
console.log(total(num)); //60
```
In this way we don't need to "update" the total variable, because is a function, and it's evaluated every time.

Lia Seltene · Answer

Ohhh okay. It gets evaluated once, and if you want it to say something different but keep the other variable within it for some reason, you do have to start over kinda?
so with that example
```javascript
var num = 10;
var total = 100 - num;
num = 20;
var x = 2;
total *= x;
```
That will make the total = 180 and not 160. But if I do:
```javascript
var num = 10;
var total = 100 - num;
num = 20;
var x = 2;
total = 100 - num;
total *= x;
```
Then the total will be 160. Is that right?

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Lia Seltene

Lia Seltene

You have to update variables if it contains another variable that has been modified??

3 Answers

Ignazio Calo

Ignazio Calo

Ignazio Calo

Ignazio Calo

Lia Seltene

Lia Seltene

Lia Seltene

Lia Seltene