Loops: for and while

for and while repeat until a condition fails. Prefer for...of for arrays when you need values.

• for (let i = 0; i < n; i++) is classic indexing.
• for...of iterates values; for...in iterates keys (use carefully).
• break exits early; continue skips one iteration.

let sum = 0;
for (let i = 1; i <= 3; i++) sum += i;
console.log(sum);

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