Simple destructuring Array/Object in ES6

Question

I am trying to return new object with selected keys - reqProps. I managed to do it with fixes props prop1, prop3 and now want to be able to pass reqProps array values to replace prop1, prop3. I tried function, and string literals and few 'hacks'. None of them worked

const data = [
  {
    prop1: 1,
    prop2: 2,
    prop3: 3
  },
  {
    prop1: 10,
    prop2: 20,
    prop3: 30
  },
  {
    prop2: 200,
    prop4: 400
  },
  {
    prop3: 3000
  }
];

// to return properties for the following...
const reqProps = ['prop2','prop3','prop4'];

// current implementation fixing return object with prop1, prop3
const obj = data.map(({prop1, prop3}) => {
    return {prop1, prop3};
});

The result of obj for the moment is

[{"prop1":1,"prop3":3},{"prop1":10,"prop3":30},{},{"prop3":3000}]

I do not want to use loops, quite like the 'power' of destructuring! ;)

Answer 1

If you insist on destructuring, you have to use eval:

const reqProps = ['prop2','prop3','prop4'];

const literalString = '{'+reqProps.join(',')+'}';

const obj = data.map(new Function(literalString, 'return '+literalString));

You really should use a loop - you can also hide it in a helper function or just use reduce.

Answer 2

As @Bergi suggests, you'd better use loops in some way.

Here's a variant with implicit loops:

data.map(o => reqProps.filter(p => p in o)
                      .reduce((acc, p) => ({...acc, [p]: o[p]}), {}))