JSON.stringify an object with a blob

Question

I have an object with an audio blob inside of it. When I call JSON.stringify on the object, the blob disappears. How to stringify a binary blob in an object ?

The audio blob is from the sox-element and in this case is of mime type 'audio/wav'.

let blob = this/soxElem.getBlob();
let object = {
  audio: blob,
  name: "hi"
}

console.log(JSON.stringify(object))

The console shows {audio:{}, name: "hi"}. The blob is gone.

it may be, blob is a datatype and you are returning string datatype — tejesh
– tejesh, Commented May 20, 2021 at 3:53
The blob isn't gone, it just is an object that has no enumerable properties: {}. What result do you expect? JSON has no type for binary data. — Bergi
– Bergi, Commented May 20, 2021 at 4:06

Matt · Accepted Answer · 2021-05-20 04:53:46Z

2

One way to do it is to convert to an array which JSON can handle :

let ab = await this.soxElem.getBlob().arrayBuffer();
let object = {
  audio: Array.from(new Uint8Array(ab)),
  name: "hi"
}

On the receiving side (e.g. with Node.js) decode it like so :

let binaryData = Buffer.from(data.audio);

answered May 20, 2021 at 4:53

Matt

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2 Comments

Kaiido Over a year ago

If it's to send that data to a server they'd be better sending it as multipart from the beginning. This encoding to JSON will be even bigger than a base64 encoding which is already ~37% bigger than the binary data it represents.

Matt Over a year ago

What do you think is a btter way ?

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