index.js

'use strict'

const crypto = require('crypto')

function _serialize(obj) {
  if (Array.isArray(obj)) {
    return `[${obj.map(el => _serialize(el)).join(',')}]`
  } else if (typeof obj === 'object' && obj !== null) {
    let acc  = ''
    const keys = Object.keys(obj).sort()
    acc += `{${JSON.stringify(keys)}`
    for (let i = 0; i < keys.length; i++) {
      acc += `${_serialize(obj[keys[i]])},`
    }
    return `${acc}}`
  }

  return `${JSON.stringify(obj)}`
}

/**
 * Serializes a JSON object (not any random JS object).
 *
 * It should be noted that JS objects can have members of
 * specific type (e.g. function), that are not supported
 * by JSON.
 *
 * @param {Object} obj JSON object
 * @returns {String} stringified JSON object.
 */
function serialize (obj) {
  return _serialize(obj, '')
}

/**
 * Creates hash of given JSON object.
 *
 * @param {Object} obj JSON object
 * @param {String} hashAlgorithm hash algorithm (e.g. SHA256)
 * @param {String} encoding hash encoding (e.g. base64) or none for buffer
 * @see #serialize
 */
function digest (obj, hashAlgorithm, encoding) {
  const hash = crypto.createHash(hashAlgorithm)
  return hash.update(serialize(obj)).digest(encoding)
}

module.exports = {
  stringify: () => {
    throw new Error('"stringify()" is deprecated, use "serialize()" instead!')
  },
  serialize: serialize,
  digest: digest
}