Bitcoin Wallet Import Format encoding/decoding module.
import * as wif from "wif"
var privateKey = Buffer.from('0000000000000000000000000000000000000000000000000000000000000001', 'hex')
var key = wif.encode({version: 128, privateKey, compressed: true}) // for the testnet use: wif.encode(239, ...
// => KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU73sVHnoWn
var obj = wif.decode(key)
// => {
// version: 128,
// privateKey: Uint8Array(32) [
// 0, 0, 0, 0, 0, 0, 0, 0, 0,
// 0, 0, 0, 0, 0, 0, 0, 0, 0,
// 0, 0, 0, 0, 0, 0, 0, 0, 0,
// 0, 0, 0, 0, 1
// ],
// compressed: true
//}
wif.decode(key, 0x09)
// => Error: Invalid network version
// alternative syntax
wif.encode(obj)
// => KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU73sVHnoWn