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Updated: 2026年5月31日

Array First Element

Original task (JA): 配列の先頭

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Conclusion

Array First Element — free browser-based JavaScript practice

■ What this exercise teaches fruitsの最初の要素をconsole.logで出力してください。fruitsは['りんご','みかん','ぶどう']。

Why it matters in real projects

配列は0から始まるインデックスでアクセスします。 Similar patterns appear daily in code review and production UI work.

Step-by-step workflow

1. Read the guide and understand the goal of "Array First Element" 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: りんご. 6. After success, continue with adjacent exercises in the same category

Core concept explained

配列は0から始まるインデックスでアクセスします。

Technical focus

Key JavaScript APIs: console.log.

Hint before you peek at the solution

fruits[0] で最初の要素

Sample solution walkthrough

JavaScript APIs used: console.log. Verify spelling and async/await usage. Explanation: 配列は0から始まるインデックスでアクセスします。 Hint recap: fruits[0] で最初の要素

Solution code

📝 Sample code
const fruits = ['りんご', 'みかん', 'ぶどう'];
console.log(fruits[0]);

Common mistakes for this exact task

・Skipping the hint: fruits[0] で最初の要素

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: りんご. 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 "Array First Element" 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.log

What 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 配列の先頭, js-basic, 入門, console.log, array first element—search-friendly guide for Array First Element.

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■ Exercise task

fruitsの最初の要素をconsole.logで出力してください。fruitsは['りんご','みかん','ぶどう']。

Hint if stuck

fruits[0] で最初の要素

10pt

配列の先頭

fruitsの最初の要素をconsole.logで出力してください。fruitsは['りんご','みかん','ぶどう']。

エラーをクリックで該当行をハイライト。✕=エラー ⚠=警告 ›=ログ。

Roadmap · All guides

Deep dive

"Array First Element" is a 入門-level JavaScript exercise. fruitsの最初の要素をconsole.logで出力してください。fruitsは['りんご','みかん','ぶどう']。 Run it in-browser with automatic checking.

配列は0から始まるインデックスでアクセスします。 Similar patterns appear daily in code review and production UI work.

Pair this with the js-basic roadmap. Exercise #48 reinforces core js-basic skills.

Step-by-step workflow

  1. Read the guide and understand the goal of "Array First Element"
  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: りんご.
  6. After success, continue with adjacent exercises in the same category

How to read the sample solution

JavaScript APIs used: console.log. Verify spelling and async/await usage. Explanation: 配列は0から始まるインデックスでアクセスします。 Hint recap: fruits[0] で最初の要素

Real-world & career relevance

JS basics precede React, Vue, and Node. Variables, functions, and arrays appear in daily code review.

Common mistakes

  • Skipping the hint: fruits[0] で最初の要素
  • Typos in console.log
  • Loose == between string and number
  • Reassigning const
  • Missing semicolons causing odd line breaks

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: りんご. 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 "Array First Element" 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.log

Glossary

const
Constant binding—no reassignment.
function
Reusable block of code.
console.log
Print to the developer console.

Keywords covered on this page

Free hands-on exercise covering 配列の先頭, js-basic, 入門, console.log, array first element—search-friendly guide for Array First Element.

Related dev tools

Learning roadmap

Learning roadmap →

Related exercises

Frequently asked questions

Is "配列の先頭" free?

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

Difficulty and time?

"配列の先頭" is level "入門". 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 learning roadmap.

Works on mobile?

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

Where are other exercises?

All exercises: /en/learn/ with category filters.

Key takeaway for "配列の先頭"?

配列は0から始まるインデックスでアクセスします。 Hint: fruits[0] で最初の要素

Where does js-basic fit?

JS basics precede React, Vue, and Node. Variables, functions, and arrays appear in daily code review.

Step-by-step for "Array First Element"?

1. Read the guide and understand the goal of "Array First Element"
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: りんご.
6. After success, continue with adjacent exercises in the same category

How to read the sample solution?

JavaScript APIs used: console.log. Verify spelling and async/await usage.

Explanation: 配列は0から始まるインデックスでアクセスします。

Hint recap: fruits[0] で最初の要素

Something is not working?

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: りんご. 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.

Career / interview angle?

Explain the techniques in "Array First Element" 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.log

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?

10pt is a difficulty hint, not a score you must maximize.