JavaScript Loops

A loop repeats work.

Instead of copying the same line ten times, you write one loop.

Think of a train going around a track until you say stop.

Why loops exist

Repeating by hand is boring and easy to mess up.

Loops keep the steps in one place.

Counting loops

for and while are great when you know how to count.

You start, you test, you update.

List loops

Some loops walk through arrays or objects.

for...of, for...in, and forEach will show up soon.

break and continue

break leaves the loop early.

continue skips the rest of this round and goes to the next.

Avoid forever loops

If the stop condition never becomes false, the loop never ends.

Always make sure something moves toward the end.

Tip: Before writing a loop, say what should change each time and when it should stop.