Time: 0:00
Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).
This bug belongs to the logic errors pattern
The wrong operator, an inverted condition, a formula the right way round but backwards.
What went wrong: In JavaScript, all objects including empty arrays are truthy (Boolean([]) === true), so !tags evaluates to false when tags is [].
The fix: Explicitly check that the array is non-empty: if (!tags || tags.length === 0)
Remember: In JavaScript, empty arrays [] and empty objects {} are truthy.
The pattern behind it: logic errors.
Paste this into any web page or blog post. Visitors fix the bug right there, in their browser.
<iframe src="https://trybughunt.com/embed/9aba7874-ab97-46db-ac02-28e61cc60e8d" title="Debugging challenge: Empty array evaluated in boolean condition returns true" width="100%" height="580" loading="lazy" style="border:1px solid #d4d4d8;border-radius:12px;max-width:760px"></iframe>
<p style="font-size:14px">Debugging challenge from <a href="https://trybughunt.com/challenges/9aba7874-ab97-46db-ac02-28e61cc60e8d">TryBugHunt</a></p>