How do I adapt the example in the Usage section to work in React Native?

import crypto from 'isomorphic-webcrypto'

crypto.subtle.digest(
  { name: 'SHA-256' },
  new Uint8Array([1,2,3]).buffer
)
.then(hash => {
  // do something with the hash buffer
})

This does not work as is in React Native. I have tried the following, but I’m not really sure how to get the values into the digest function. I just want to prove it works as it should.

    const view = new Int8Array( new ArrayBuffer(3));
    crypto.subtle.digest(
      { name: 'SHA-256' },
      view
    )
    .then(hash => {
      // do something with the hash buffer
      console.log('hash: ', hash);
    });

Thanks!

[kevlened]

I added additional details about hashing to the README. I also included an example of how to generate a hash in the React Native examples.

[kevlened]

It should return an ArrayBuffer. If you perform toString() on that you’ll get something like ArrayBuffer []. Brief explanation:

An ArrayBuffer is an untyped array that just represents a chunk of memory with a defined length. In order to get a view of that memory, you have to cast it to a typed array. Often, this is a Uint8Array. The U makes it unsigned, so it’s alway positive and the 8 makes each element represent one byte.

I imagine what you want is a SHA256 hash as a string. This is most commonly represented in hex. I wrote hex-lite to make this easy, so here’s an example:

import crypto from 'isomorphic-webcrypto';
import hex from 'hex-lite';

crypto.subtle.digest(
  { name: 'SHA-256' },
  new Uint8Array([1,2,3]).buffer
)
.then(hash => {
  console.log('sha256 hash', hex.fromBuffer(hash));
});