💡 An editor is ready below the article—experiment freely!
Updated: 2026年5月31日
For Loop
Original task (JA): forループ
📌
Conclusion
For Loop — free browser-based JavaScript practice
Why it matters in real projects
forで繰り返し。i++はiを1増やす。 Similar patterns appear daily in code review and production UI work.Step-by-step workflow
1. Read the guide and understand the goal of "For Loop" 2. Review the JavaScript editor pane and start from the starter code 3. Open hints if stuck; compare your diff with the sample solution 4. Click Run and inspect preview/console output 5. Auto-check looks for output containing: 1, 2, 3. 6. After success, continue with adjacent exercises in the same categoryCore concept explained
forで繰り返し。i++はiを1増やす。Technical focus
Key JavaScript APIs: console.log.Hint before you peek at the solution
for (let i = 1; i <= 5; i++) { console.log(i); }Sample solution walkthrough
JavaScript APIs used: console.log. Verify spelling and async/await usage. Explanation: forで繰り返し。i++はiを1増やす。 Hint recap: for (let i = 1; i <= 5; i++) { console.log(i); }Solution code
📝 Sample code
for (let i = 1; i <= 5; i++) {
console.log(i);
}Common mistakes for this exact task
・Skipping the hint: for (let i = 1; i <= 5; i++) { console.log(i); }Troubleshooting
Q: Preview does not change after Run A: Ensure you edited the JavaScript pane and clicked Run. Q: Looks correct but check fails A: Auto-check looks for output containing: 1, 2, 3. Look for typos, full-width spaces, or unclosed tags. Q: Console shows errors A: Open DevTools Console and fix bracket/quote mismatches at the reported line. Q: Hard to type on mobile A: Use landscape mode or continue on desktop—the same URL keeps progress in localStorage.Interview / portfolio tips
・Explain the techniques in "For Loop" in your own words within 30 seconds ・Practice walking through each line of the sample solution on a whiteboard ・Connect this task to a real component you would ship ・Mention responsive or accessibility trade-offs ・Describe when you use: console.logWhat to do after you pass
Move to the next exercise in the js-basic track, then continue the learning roadmap at /en/learning/js-basic/.Keywords
Free hands-on exercise covering forループ, js-basic, 入門, console.log, for loop—search-friendly guide for For Loop.🧪 Try it here — safe to break things
Use the editor below to write code and preview instantly.
Jump to editor■ Exercise task
1から5までをconsole.logで出力してください。
Hint if stuck
for (let i = 1; i <= 5; i++) { console.log(i); }