Browser & Web Performance · Junior · Question 42 of 75

Why do build tools put a content hash in file names like `app.3f9a1c.js`?

1To make the file smaller
2To prevent the file from being cached
✓Correct answer: So the file can be cached for a very long time; a change produces a new name and a new URL

Explanation

Hashed assets can use Cache-Control: max-age=31536000, immutable. The HTML that references them is cached briefly or revalidated.

Further reading

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