How to find the content-length of a readable stream in nodejs?

Question

I need to know the content-length of a readable stream. How can I do it?

I know about fs.stat but I am developing an API that knowing the content-length from a readable stream would be much simpler.

Answer 1

the idea behind the stream is that you start working on data before the source finishes. thus, you don't know the content-length.

if the underlying source is an HTTP object, then you could check stream.headers['content-length'], but even that is not ultimately reliable as the client or the server could have lied.

in short, you can't. personally, i'd rather just store it on disk temporarily.