for For loop
Last updated: 2026-09-09
for For loop
A for loop has init, condition and update parts — ideal for counted iteration.
| Category | Statements |
|---|---|
| ES version | ES1 |
📝 Syntax
for (let i = 0; i < N; i++) { ... }Returns：undefined.
Mutates the original：No (returns a new value)
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
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1
0
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10💡 Tip Use let for loop variables — var causes closure issues.
ℹ️ info All three parts are optional — for(;;) is an infinite loop.
🌐 Browser support
| Browser |  Chrome |
 Edge |
 Firefox |
 Safari |
 Opera |
|---|---|---|---|---|---|
| for | ✓ v1 | ✓ v12 | ✓ v1 | ✓ v1 | ✓ v1 |
| Supported by all modern browsers | |||||
🏷️ Related Items
💡 Related Cases
More case studies coming soon — check back later.
📚 Related Tutorials
❓ FAQ
Qfor vs for...of?
Afor for counted loops; for...of for iterables.
Qlet or var for loop variable?
AUse let — var causes closure issues.
QCan for loop over objects?
ANo — use for...in or Object.keys() + for...of.
