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Updated: 2026年5月31日
Project Timer
Original task (JA): タイマー
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Conclusion
Project Timer — free browser-based JavaScript practice
Why it matters in real projects
setTimeoutで指定ミリ秒後に処理を実行できます。 Similar patterns appear daily in code review and production UI work.Step-by-step workflow
1. Read the guide and understand the goal of "Project Timer" 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: 時間です. 6. After success, continue with adjacent exercises in the same categoryCore concept explained
setTimeoutで指定ミリ秒後に処理を実行できます。Technical focus
Key JavaScript APIs: console.log.Hint before you peek at the solution
setTimeout(() => { ... }, 3000)Sample solution walkthrough
JavaScript APIs used: console.log. Verify spelling and async/await usage. Explanation: setTimeoutで指定ミリ秒後に処理を実行できます。 Hint recap: setTimeout(() => { ... }, 3000)Solution code
📝 Sample code
setTimeout(() => {
console.log('時間です');
}, 3000);Common mistakes for this exact task
・Skipping the hint: setTimeout(() => { ... }, 3000)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: 時間です. 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 "Project Timer" 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 project track, then continue the learning roadmap at /en/learning/project/.Keywords
Free hands-on exercise covering タイマー, project, 中級, console.log, project timer—search-friendly guide for Project Timer.🧪 Try it here — safe to break things
Use the editor below to write code and preview instantly.
Jump to editor■ Exercise task
3秒後に「時間です」とconsole.logで出力してください。
Hint if stuck
setTimeout(() => { ... }, 3000)