postForm's form-data serialization breaks for Blob in Node.js

[exchgr]

postForm's form-data serialization breaks for Blob in Node.js

[DigitalBrainJS]

Axios supports Node v12 and above, so we can't just go the easy way and use the latest built-ins but have to support different formData implementations, as Axios is designed to be as flexible as possible.
In Axios 1.x, form-data is the default implementation. It does not support Blobs, but Streams and Buffers and doesn't follow web specs. Before version 2.x, it is not possible to change the usage priority of the FormData implementations without introducing breaking changes. And most likely even in the next major version, form-data support will still be relevant, because a lot of educational materials and codebases use it.
So for now you can either use streams/buffers in the context of the form-data module

const {data} = await axios.postForm('http://httpbin.org/post', {
  x: 1,
  stream: fs.createReadStream('1.txt')
});

or set another(native) FormData implementation as default.

const {data} = await axios.postForm('http://httpbin.org/post', {
  x: 1,
  blob: await fs.openAsBlob('2.txt')
}, {
  env: {
    FormData // native FormData constructor
  }
});