Question 1

How do I create an object stream with through2?

Accepted Answer

Use the through2.obj() wrapper, which automatically sets objectMode: true. For example, through2.obj(function(chunk, enc, cb) { this.push(processedChunk); cb(); }) creates a transform stream for objects, simplifying data pipelines.

Question 2

Through2 vs native Node.js Transform: which is better?

Accepted Answer

For modern Node.js (v10+), native Transform with simplified construction is often sufficient and avoids extra dependencies. Through2 shines with older versions or if you prefer its functional API for quick, concise transformations without subclassing.

Question 3

How to handle errors in through2 streams?

Accepted Answer

Pass errors to the callback in the transformFunction, e.g., callback(err). Also, listen for 'error' events on the stream instance to catch and handle errors appropriately in your pipeline.

Question 4

Can through2 be used for passthrough streams?

Accepted Answer

Yes, by not providing a transformFunction, through2 creates a simple passthrough stream. For instance, through2() will pass data unchanged, useful for testing or basic piping scenarios.

Question 5

What Node.js versions does through2 support?

Accepted Answer

Through2 supports older Node.js versions, but the README notes it's redundant for versions with simplified stream construction. Check the package.json or npm registry for specific compatibility details, typically back to earlier Node.js releases.

Question 6

How to create a reusable transformer with through2?

Accepted Answer

Use through2.ctor() to create a constructor, e.g., const MyTransform = through2.ctor(options, transformFn). Then instantiate it with new MyTransform() or MyTransform() for multiple streams with the same logic.

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