The Infinite Loop, and How to Avoid It

Every while loop needs three things. Miss any one and it runs forever:

1. A variable initialized before the loop

2. A condition that can eventually become false

3. Something inside the loop that moves toward that false

Forget step 3 and the condition never changes. The program hangs.

✦ You are protected here

The Sankofa sandbox stops runaway JavaScript after four seconds and tells you what happened, so you can experiment without fear. On your own machine there's no such net, Ctrl+C is how you stop it. Learning to spot the missing update is the real skill.