Transform a nested object insto a nested Map object

populateMap.js

/**
 * Populate a map with the values of an object with nested maps
 * 
 * @param {Map}    map    - Map to populate
 * @param {object} object - Object to use for the population
 * @param {array}  keys   - Array of keys of the object
 * 
 * @return {Map} Populated map
 */
function populateMap (map, object, keys) {
  // Return the map once all the keys have been populated
  if (!keys.length) return map

  let key = keys.shift()
  let value = object[key]

  if (typeof value === 'object') {
    // When value is an object, we transform every key of it into a map
    value = populateMap(new Map(), value, Object.keys(value))
  }

  // Set the value into the map
  map.set(key, value)

  // Recursive call
  return populateMap(map, object, keys)
}

/**
 * Example usage:
 */
let myMap = new Map()
let myObject = {
  a: { b: 1, c: 2 }
}

populateMap(myMap, myObject, Object.keys(myObject))

// that is the equivalent of doing:
let a = new Map()
a.add(b, 1)
a.add(c, 2)

myMap.add('a', a)