Adapted from Jazzicon by Dan Finlay with the following changes -

• Random values now is read from the Uint8Array supplied (as opposed to having the seed as a number). This allows us to give an publicKey/address as an input and use those values in the pattern generation.
• Upgrade to the underlying color library
• Generate circles as shapes (instead of rectangles)
• Interface updated to take in optional className & style
• Update everywhere to use ES6
• Split source into self-contained functions (TODO: future testing)
• Everything has been updated to use flow
• Test the library functions
• Copyright headers added (original also under ISC)

import identicon from '@tsiry/ui-identicon';

const publicKey = new Uint8Array([...]); // 32 bytes
const body = document.querySelector('body');
const identity = identicon(publicKey, 100 /* diameter, optional */, 'my-class' /* className, optional */ /* style. optional */ /* colors, optional */);

body.append(identity);

Also see src/demo.js for a randomly generated example.