Slice specific keys in javascript object

Question

In rails, i have a special slice method to keep in Hash only keys I need. It is very handy to permit only required keys in a hash.

Is there a method like this in Node.js?

Answer 1

These are the coolest solutions.

Hard corded version: https://stackoverflow.com/a/39333479/683157

const object = { a: 5, b: 6, c: 7  };
const picked = (({ a, c }) => ({ a, c }))(object);

console.log(picked); // { a: 5, c: 7 }

Generic version: https://stackoverflow.com/a/32184094/683157

const pick = (...props) => o => props.reduce((a, e) => ({ ...a, [e]: o[e] }), {});
pick('color', 'height')(elmo);

Answer 2

In JavaScript there is no such method, however, in libraries like lodash there is the method called _.pick

var data = { a: 1, b: 2, c: 3 };
console.log(_.pick(data, 'a', 'c'))

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.1/lodash.js"></script>

you can install lodash via npm

npm install lodash --save

and then require it to your project

var _ = require('lodash') // import all methods
// or just import pick method
// var pick = require('lodash/object/pick');

Or you can implement your own pick with new ES features, like so

const data = { a: 1, b: 2, c: 3 };

const pick = (obj, ...args) => ({
  ...args.reduce((res, key) => ({ ...res, [key]: obj[key] }), { })
})

console.log(
  pick(data, 'a', 'b')
)