Reading a blob synchronous in javascript

mod.js

const blob = new Blob(['123'])
const xhr = new XMLHttpRequest()
const url = URL.createObjectURL(blob)

// required if you need to read binary data:
xhr.overrideMimeType('text/plain; charset=x-user-defined') 
xhr.open('GET', url, false)
xhr.send()

const uint8 = Uint8Array.from(xhr.response, c => c.charCodeAt(0))
const text = new TextDecoder().decode(uint8)
const arrayBuffer = uint8.buffer
const json = JSON.parse(text)