JavaScript mapping and filtering a basic array of objects

Question

Having this array

[ { name: 'foo', gender: 'm' }, { name: 'bar', gender: 'f' }, { name: 'baz', gender: 'f' }  ]

How is it (maybe in a one-liner) possible to transform it into:

[ { gender: 'f', names: [ { name: 'bar' }, { name: 'baz' } ] } ]

Filtered by gender Vanilla JS, ES6 and/or ES7.

Hi! Please take the tour and read through the help center, in particular How do I ask a good question? Do your research, search for related topics on SO, and give it a go. If you get stuck and can't get unstuck after doing more research and searching, post a minimal reproducible example of your attempt and say specifically where you're stuck. People will be glad to help. Good luck! — T.J. Crowder
– T.J. Crowder, Commented May 23, 2018 at 7:36
(FWIW, map wouldn't really apply here. filter would in some solutions, not in others.) — T.J. Crowder
– T.J. Crowder, Commented May 23, 2018 at 7:37

Nina Scholz · Accepted Answer · 2018-05-23 07:44:34Z

2

You could filter by gender and map objects with name.

var array = [{ name: 'foo', gender: 'm' }, { name: 'bar', gender: 'f' }, { name: 'baz', gender: 'f' }],
    object = { gender: 'f', names: array
        .filter(({ gender }) => gender === 'f')
        .map(({ name }) => ({ name }))
    };

console.log(object);

answered May 23, 2018 at 7:44

Nina Scholz

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Hassan Imam · Accepted Answer · 2018-05-23 07:40:27Z

0

You can use array#reduce to group your data based on gender in an object accumulator. Then get all the values from this object using Object.values().

const data = [ { name: 'foo', gender: 'm' }, { name: 'bar', gender: 'f' }, { name: 'baz', gender: 'f' }  ],
      group = Object.values(data.reduce((r, {name, gender}) => {
        r[gender] = r[gender] || {gender, names : []};
        r[gender].names.push({name});
        return r;
      },{}));
console.log(group);

answered May 23, 2018 at 7:40

Hassan Imam

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