4.2 For Loop

For loops run a block of code for based on a condition that is updated at every iteration of the loop.

Basic Structure

This is what a typical for loop looks like:

for (statement 1; statement 2; statement 3) {
	// code that runs
}

Statement 1: Initialization

This executes just ONCE before the execution of the code in the for statement.

Statement 2: Condition

This is the condition that is checked before the execution of the code in the for loop.

Statement 3: Iterator

This is executed every time the code in the for loop finished.

Example

Here's an example of a for loop:

let total = 0;
for (int i = 0; i < 5; i++) { // 0 + 1 + 2 + 3 + 4
    total += i;
}

// total = 10

You don't always need to include statement 1 or 3. You DO need a statement 2. So, this is allowed:

let i = 0;
let total = 0;
for (; i < 5;) { // 0 + 1 + 2 + 3 + 4
    total += i;
    i++;
}

Practice

You can add practice problems here if you want. Follow the format below.

💻 Template code

✅ Solution code