JavaScript Variables

A variable is a labeled box that holds a value.

You put something in. Later you can look at it or change it.

Think of a cookie jar with a name tag on the lid.

Declaration

Declaration means making the box and giving it a name.

Here we make a box called savings:

Assignment

Assignment means putting a value inside with =.

The name is on the left. The value is on the right.

Re-assignment

Re-assignment means changing what is inside the same box.

The name stays. The value can grow or shrink.

Declaration and assignment together

You can make the box and fill it in one line.

That is the usual way to start.

Good names

Pick names that tell the truth.

score is clearer than s. userAge is clearer than x.

Your future self will thank you.

Tip: First make the box. Then put something in. Then change it only when you need to.