Howard Zuo created ARROW-12636:
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Summary: [JS] ESM Tree-Shaking produces broken code
Key: ARROW-12636
URL: https://issues.apache.org/jira/browse/ARROW-12636
Project: Apache Arrow
Issue Type: Bug
Components: JavaScript
Affects Versions: 4.0.0
Reporter: Howard Zuo
When a JS application depends on `apache-arrow` or any of the ESM variants,
Arrow's package.json declares `sideEffects: false` which allows bundlers like
Webpack or Rollup to remove all code that's evaluated at the top level of all
modules (any code that isn't explicitly imported can be pruned).
However, there are important top-level side effects that arrow relies on, e.g.
for binding methods on types:
[https://github.com/apache/arrow/blob/c0445d69088a6fbd9c026ecac6a99c6cd4df4865/js/src/vector/index.ts#L167-L179]
So currently, any JS app that uses tree-shaking and depends on `apache-arrow`
or the ESM variants will throw if any of those methods are called, e.g. in my
case I see `TypeError: e._chunks[t].get is not a function`.
Indeed switching to the CJS variants like `@apache-arrow/es2015-cjs` fixes the
issue.
For reference, the `sideEffects: false` logic was introduced in this PR and
issue:
[https://github.com/apache/arrow/pull/8418/]
https://issues.apache.org/jira/browse/ARROW-10255
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