Reduce array of objects into object [duplicate]

Answer 1

Using Array#forEach.

var data = [ { name: 'foo', type: 'fizz', val: 9 }, { name: 'boo', type: 'buzz', val: 3 }, { name: 'bar', type: 'fizz', val: 4 }, { name: 'car', type: 'buzz', val: 7 }, ], 
    res = {};
    data.forEach(v => res[v.val] = v.name);

    console.log(res);

Using Array#reduce.

var data = [ { name: 'foo', type: 'fizz', val: 9 }, { name: 'boo', type: 'buzz', val: 3 }, { name: 'bar', type: 'fizz', val: 4 }, { name: 'car', type: 'buzz', val: 7 }, ],
    res = data.reduce(function(s,a){
      s[a.val] = a.name;
      return s;
    }, {});
  
    console.log(res);

Answer 2

You could use Object.assign and map the objects with generated computed property names and values.

var data = [{ name: 'foo', type: 'fizz', val: 9 }, { name: 'boo', type: 'buzz', val: 3 }, { name: 'bar', type: 'fizz', val: 4 }, { name: 'car', type: 'buzz', val: 7 }],
    object = Object.assign({}, ...data.map(o => ({ [o.val]: o.name })));

console.log(object);

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Answer 3

Something like this should work:

const data = [
  { name: 'foo', type: 'fizz', val: 9 },
  { name: 'boo', type: 'buzz', val: 3 },
  { name: 'bar', type: 'fizz', val: 4 },
  { name: 'car', type: 'buzz', val: 7 },
];

const reduced = data.reduce((acc, item) => {
  acc[item.val] = item.name;
  return acc;
}, {});

console.log(reduced);