while and do...while Loops

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Lesson format7 sections1 code block1 practice itemUpdated Aug 23, 2026

#Control flow is where small syntax choices turn into program behavior. Good logic makes invalid states obvious instead of hiding them behind nested branches. In this lesson, the practical target is while and do...while loops: you should be able to predict what the runtime will do before changing the code.#link

Question to ask	Good diagnostic move
What value entered?	Inspect the runtime value and type.
What rule applied?	Check the construct's language or host semantics.
What changed?	Compare the smallest working and failing cases.

javascript

let attempts = 0;
while (attempts < 3) {
  attempts += 1;
}
console.log(attempts);

Live JavaScript preview

<strong>Core idea:</strong> Control flow is where small syntax choices turn into program behavior. Good logic makes invalid states obvious instead of hiding them behind nested branches. In this lesson, the practical target is while and do...while loops: you should be able to predict what the runtime will do before changing the code.

Core idea: Control flow is where small syntax choices turn into program behavior. Good logic makes invalid states obvious instead of hiding them behind nested branches. In this lesson, the practical target is while and do...while loops: you should be able to predict what the runtime will do before changing the code.

★ 20 XP

exercise BLOCK (★ 20 XP)

Which statement best matches the behavior taught in “while and do...while Loops”?

Select your proof vectors above

STRICT SECURE AUDIT RULE

Mentor note: for while and do...while loops, name the invariant you need before reaching for a clever shortcut. Clear state and explicit assumptions make later debugging much cheaper.

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Finish the lesson once you have worked through the material. This awards ★ 20 XP.

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Control flow is where small syntax choices turn into program behavior. Good logic makes invalid states obvious instead of hiding them behind nested branches. In this lesson, the practical target is while and do...while loops: you should be able to predict what the runtime will do before changing the code.

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August 23, 2026

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Laboratory sanity code

Isolate active probes on matched virtual networks and keep execution streams sandboxed.

Question to ask

Good diagnostic move

What value entered?

Inspect the runtime value and type.

What rule applied?

Check the construct's language or host semantics.

What changed?

Compare the smallest working and failing cases.