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Updated: 2026年5月31日
Api Error Handling
Original task (JA): エラーハンドリング
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Conclusion
Api Error Handling — free browser-based JavaScript practice
Why it matters in real projects
res.okでHTTPステータスが成功かどうか判定します。 Similar patterns appear daily in code review and production UI work.Step-by-step workflow
1. Read the guide and understand the goal of "Api Error Handling" 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: sunt, aut, title. 6. After success, continue with adjacent exercises in the same categoryCore concept explained
res.okでHTTPステータスが成功かどうか判定します。Technical focus
Key CSS properties: https.Hint before you peek at the solution
if (!res.ok) { ... } else { ... }Sample solution walkthrough
JavaScript APIs used: console.log, fetch(, async , await . Verify spelling and async/await usage. Explanation: res.okでHTTPステータスが成功かどうか判定します。 Hint recap: if (!res.ok) { ... } else { ... }Solution code
📝 Sample code
async function run() {
const res = await fetch('https://jsonplaceholder.typicode.com/posts/1');
if (!res.ok) {
console.log('エラー');
} else {
const data = await res.json();
console.log(data.title);
}
}
run();Common mistakes for this exact task
・Skipping the hint: if (!res.ok) { ... } else { ... } ・Forgetting await res.json() leaves you with a Promise objectTroubleshooting
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: sunt, aut, title. 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 "Api Error Handling" 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 ・Discuss CSS properties: https ・Describe when you use: console.log, fetch(, asyncWhat to do after you pass
Move to the next exercise in the api track, then continue the learning roadmap at /en/learning/api/.Keywords
Free hands-on exercise covering エラーハンドリング, api, 中級, https, console.log, fetch(, async , await , api error handling—search-friendly guide for Api Error Handling.🧪 Try it here — safe to break things
Use the editor below to write code and preview instantly.
Jump to editor■ Exercise task
fetchで取得し、res.okがfalseなら「エラー」とconsole.log、trueならデータのtitleを出力してください。
Hint if stuck
if (!res.ok) { ... } else { ... }