Unary Operators: The Magic “Before and After” Buttons in JavaScript
Imagine you have a magical scoreboard in a video game. Sometimes, you want to see your score go up right now, and other times, you want to finish your turn before the score changes. In the world of JavaScript, we use special symbols called Unary Operators to do this!
“Unary” sounds like a big word, but it just means these symbols work on one thing at a time (like a single number). We use ++ to add one and -- to take one away.
1. The Postfix Operator: “After You!”
The Postfix Operator is like a polite friend who lets everyone else go first. You write it with the symbols after the name, like x++.
When you use this, JavaScript says: “I’ll use the number you have right now for this job, and then I’ll add one to it once I’m done.”
Example:
let apples = 5;
console.log(apples++); // It shows 5!
console.log(apples); // Now it shows 6.
- let: This is a keyword we use to create a “box” (variable) to store information.
- apples: This is the name we gave our box.
- console.log(): This is a built-in function that “prints” or shows us what is inside a box on our computer screen.
2. The Prefix Operator: “Me First!”
The Prefix Operator is a bit more impatient. You write the symbols before the name, like ++x.
When you use this, JavaScript says: “Stop everything! Add one to this number first, and then use the new version for the rest of the work.”
Example:
let oranges = 5;
console.log(++oranges); // It shows 6 immediately!
The Comparison Table
| Type | How it looks | What happens? |
|---|---|---|
| Postfix | x++ |
Use the old value first, then change it. |
| Prefix | ++x |
Change it first, then use the new value. |
Putting it All Together
What happens if we mix them up in a big math problem?
let score1 = 10;
let score2 = 10;
let total = score1++ + ++score2;
- score1++ says: “Use 10 for the math, then make me 11 later.”
- ++score2 says: “Make me 11 right now, then use me for the math.”
- The computer does , so the
totalis 21!
Top Tip: If you want your code to be easy to read for your friends, try to use these on their own lines so nobody gets confused about the timing!
