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Updated: May 31, 2026

Api Error Handling

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Conclusion

Api Error Handling — free browser-based JavaScript practice

■ What this exercise teaches Fetch data; if res.ok is false output "Error" with console.log, otherwise output the title.

Why it matters in real projects

res.ok tells you whether the HTTP request succeeded. 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 category

Core concept explained

res.ok tells you whether the HTTP request succeeded.

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 tells you whether the HTTP request succeeded. 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('Error');
  } 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 object

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: 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(, async

What 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 Error handling, api, intermediate, https, console.log, fetch(, async , await , api error handling—search-friendly guide for Api Error Handling.

🧪 Try it here — safe to break things

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■ Exercise task

Fetch data; if res.ok is false output "Error" with console.log, otherwise output the title.

Hint if stuck

if (!res.ok) { ... } else { ... }

25pt

Error handling

Fetch data; if res.ok is false output "Error" with console.log, otherwise output the title.

Click error to highlight line. ✕=error ⚠=warning ›=log.

Roadmap · All guides

Deep dive

"Api Error Handling" is a intermediate-level JavaScript exercise. Fetch data; if res.ok is false output "Error" with console.log, otherwise output the title. Run it in-browser with automatic checking.

res.ok tells you whether the HTTP request succeeded. Similar patterns appear daily in code review and production UI work.

Pair this with the api roadmap. Exercise #65 reinforces core api skills.

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 category

How to read the sample solution

JavaScript APIs used: console.log, fetch(, async , await . Verify spelling and async/await usage. Explanation: res.ok tells you whether the HTTP request succeeded. Hint recap: if (!res.ok) { ... } else { ... }

Real-world & career relevance

fetch + JSON appear in most real projects: weather apps, GitHub integrations, headless CMS.

Common mistakes

  • Skipping the hint: if (!res.ok) { ... } else { ... }
  • Forgetting await res.json() leaves you with a Promise object
  • Forgetting res.json() after fetch
  • Treating CORS as a code bug
  • No try-catch for network failures

Troubleshooting

Preview does not change after Run
Ensure you edited the JavaScript pane and clicked Run.
Looks correct but check fails
Auto-check looks for output containing: sunt, aut, title. Look for typos, full-width spaces, or unclosed tags.
Console shows errors
Open DevTools Console and fix bracket/quote mismatches at the reported line.
Hard to type on mobile
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(, async

Glossary

fetch
Browser API for HTTP requests.
JSON
Lightweight data interchange format.
CORS
Cross-origin browser security policy.

Keywords covered on this page

Free hands-on exercise covering Error handling, api, intermediate, https, console.log, fetch(, async , await , api error handling—search-friendly guide for Api Error Handling.

Related dev tools

Learning roadmap

Learning roadmap →

Related exercises

Frequently asked questions

Is "Error handling" free?

This exercise is free and runs entirely in your browser. No account or credit card required.

Difficulty and time?

"Error handling" is level "intermediate". Read the guide first; beginners can usually finish within 30 minutes. Allow 5–15 minutes per exercise. Use hints, then the solution if stuck.

What after a correct answer?

After a correct answer, use "Next exercise". When you finish a category, continue on the <a href="/en/learning/api/">learning roadmap</a>.

Works on mobile?

Works on mobile browsers, but typing code is easier on a desktop.

Where are other exercises?

All exercises: <a href="/en/learn/">/en/learn/</a> with category filters.

Key takeaway for "Error handling"?

res.ok tells you whether the HTTP request succeeded. Hint: if (!res.ok) { ... } else { ... }

Where does API fit?

fetch + JSON appear in most real projects: weather apps, GitHub integrations, headless CMS.

Step-by-step for "Api Error Handling"?

1. Read the guide and understand the goal of "Api Error Handling"<br />2. Review the JavaScript editor pane and start from the starter code<br />3. Open hints if stuck; compare your diff with the sample solution<br />4. Click Run and inspect preview/console output<br />5. Auto-check looks for output containing: sunt, aut, title.<br />6. After success, continue with adjacent exercises in the same category

How to read the sample solution?

JavaScript APIs used: console.log, fetch(, async , await . Verify spelling and async/await usage.<br /><br />Explanation: res.ok tells you whether the HTTP request succeeded.<br /><br />Hint recap: if (!res.ok) { ... } else { ... }

Something is not working?

<strong>Preview does not change after Run</strong> → Ensure you edited the JavaScript pane and clicked Run.<br /><strong>Looks correct but check fails</strong> → Auto-check looks for output containing: sunt, aut, title. Look for typos, full-width spaces, or unclosed tags.<br /><strong>Console shows errors</strong> → Open DevTools Console and fix bracket/quote mismatches at the reported line.<br /><strong>Hard to type on mobile</strong> → Use landscape mode or continue on desktop—the same URL keeps progress in localStorage.

Career / interview angle?

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(, async

Related dev tools?

<a href="/en/tools/json-formatter/">JSON Formatter</a>, <a href="/en/tools/jwt-decode/">JWT Decode</a>, <a href="/en/tools/dns-check/">DNS Check</a>

Prerequisites?

Read the <a href="/en/learning/api/">Learning roadmap</a> chapter first.

Can I change the starter code?

Yes—if it works. Understanding the starter first, then adding minimal diffs, speeds up learning.

What do the points mean?

25pt is a difficulty hint, not a score you must maximize.