javascript create dictionary from array

Question

I have an array like this

propertiesToCheck: [
    {name: 'name', type: 'type', enabled: true},
    {
        name: 'name2',
        type: 'type2',
        templateUrl: 'something.html',
        preferences: {
            places: [place1, place2,...],
            placesDict: ????
        },
        enabled: true
    }
]

In the places array there are objects with id, name, etc. Now I want to create a dictionary placesDict that should look like {place1.id: 0, place2.id: 0, ...}, so all values will be set to 0. How can I do that?

Answer 1

Better option in modern JS (>2019) is to use. It requires to have an Array of tuples (Array of Arrays). In following call I am extending Array with the map function which constructs the "nested array".

> const x = ["a", "b", "3"];
> Object.fromEntries(x.map(i => [i, undefined]));|
{ '3': undefined, a: undefined, b: undefined }

You can use the spread operator with following result:

> x = [1,2,3]
[ 1, 2, 3 ]
> {...x}
{ '0': 1, '1': 2, '2': 3 }

Answer 2

In Ramda for instance:

var createDict = R.pipe(R.pluck('id'), R.map(R.pair(R.__, 0)), R.fromPairs);

var places = [{ id: 'place1id' }, { id: 'place2id' }];
var placesDict = createDict(places);

// {"place1id": 0, "place2id": 0}