renameKeys.js

  function renameKeys (dict, keyMap) {
    return _.reduce(dict, function (newDict, val, oldKey) {
      var newKey
      if (keyMap[oldKey]) {
        newKey = keyMap[oldKey]
      } else {
        newKey = oldKey
      }
      newDict[newKey] = val
      return newDict
    }, {})
  }

renameKeysNested.js

  function renameKeys (dict, keyMap) {
    return _.reduce(dict, remap, {})

    function remap (newDict, val, oldKey) {
      var newKey
      if (keyMap[oldKey]) {
        newKey = keyMap[oldKey]
      } else {
        newKey = oldKey
      }

      if (val instanceof Object) {
        newDict[newKey] = _.reduce(val, remap, {})
      } else {
        newDict[newKey] = val
      }
      return newDict
    }
  }

function renameKeys (dict, keyMap) {

  function remap (newDict, val, oldKey) {
    var newKey;

    if (_.isFunction(keyMap)) {
      newKey = keyMap(oldKey);
    } else {
      newKey = keyMap[oldKey];
    }
    newKey = newKey || oldKey;

    if (val instanceof Object) {
      newDict[newKey] = _.reduce(val, remap, {})
    } else {
      newDict[newKey] = val
    }
    return newDict
  }
  return _.reduce(dict, remap, {});
}

This converts nested array to an Object. Here is the codepen link for your reference:
https://codepen.io/cksachdev/pen/NgZMYQ
Object structure

var obj = {
    children: [{
        id: "children id",
        label: "children label",
        type: 4,
        uniqueId: "children unique id" 
    }],
    id: "something",
    label: "Some label here...",
    type: 5,
    uniqueId: "This is unique."
};