generate a short sha1 hash from a file's contents
npm install sha1-from-file --save
import { createReadStream, readFileSync } from 'fs'
import hash, { sync } from 'sha1-from-file'
// async (ES6-)
hash(createReadStream('./file.txt')).then(myHash => ...)
// async (ES7)
const myHash = await hash(createReadStream('./file.txt'))
// sync (buffer)
const myHash = sync(new Buffer(...))
// sync (string)
const myHash = sync(readFileSync('./file.txt', 'utf-8')) // "1bhh17h"