Return object with subset of its attributes

Question

I've got a flat JavaScript object like this:

{ 
  id: 3726492,
  kind: 'user',
  permalink: 'nicholas',
  username: 'Nicholas',
  ...
  a lot more attributes
}

I'd like to create a new object which only has a subset of the attributes of the original object.

Something like

var newObject = oldObject.fields(['id', 'username']);

newObject would be

{ 
  id: 3726492,
  username: 'Nicholas'
}

Is there already something like this?

Answer 1

Try this

function pick(data, keys) {
  var result = {};
  
  keys.forEach(function (key) {
    if (data.hasOwnProperty(key)) {
      result[key] = data[key];
    }
  });
  
  return result;
}

var data = { 
  id: 3726492,
  kind: 'user',
  permalink: 'nicholas',
  username: 'Nicholas'
}

var newData = pick(data, ['id', 'kind']);
console.log(newData);

In underscorejs or lodash there is method .pick

var data = { 
  id: 3726492,
  kind: 'user',
  permalink: 'nicholas',
  username: 'Nicholas',
};

var newObject = _.pick(data, 'id', 'username');
console.log(newObject);

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore.js"></script>