InfoparkDailyCAREER TOOLS

JavaScript · Lesson 4 of 8

Loops

for, while, for…of and breaking out of loops.

Loops repeat code.

  • for (let i = 0; i < 5; i++) { … } — counted loops.
  • while (condition) { … } — repeat while true; make sure it ends!
  • for (const item of list) { … } — every item of an array or string.
  • break stops the loop; continue skips to the next round.

Try it yourself

Edit the code and press Run (or Ctrl/⌘ + Enter). Code runs only in your browser, in a sandbox.

Key points

  • for for counting, for…of for lists.
  • Every while loop needs an exit.
  • break / continue control the flow.

Quick check

How many times does for (let i = 0; i < 3; i++) run?

Practice task

Use a loop to calculate the total of [3.5, 6, 8, 12] and print the average.

Interview corner

for…of vs for…in?

for…of iterates values of arrays and other iterables. for…in iterates property keys of an object — avoid it for arrays.

How do you stop a loop early?

Use break. continue skips just the current iteration.

Further reading

Official documentation, linked for deeper study. These are outside sites; this lesson's text is our own.

Original lesson written by the InfoparkDaily team · © 2026 InfoparkDaily · Free to learn — no paid course or subscription.