What is tree shaking?
PICTURE THIS: DJANGO MVT
Simple meaning
Bundlers drop unused ES module exports when they can prove they are unused.
WHY — Performance instead of guessing?
Why interviewers care about Performance:
who only read docs from people who shipped.
and tied to Frontend work.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1Bundlers drop unused ES
module exports when they can prove they are unused.
- 2Side-effectful modules and CommonJS
are harder to shake.
- 3Named imports from lodash-es
rather than a default lodash import is the classic interview example.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
Bundlers drop unused ES module exports when they can prove they are unused. Side-effectful modules and CommonJS are harder to shake.