Filter Object based on an array

Question

I’ve got an object having this form:

const obj = {
    abc: "Moon",
    def: "Earth",
    asd: "Sun",
    dmg: "Venus",
    xyz: "Mars",
    tuv: "Jupiter"
};

And an array with this form:

const arr = ["abc", "def", "tuv"];

I want to filter obj based on the values given in arr. That means, is there a way, probably using the filter method, to turn obj into this:

const newObj = {
    abc: "Moon",
    def: "Earth",
    tuv: "Jupiter"
};

score 7 · Answer 1 · answered Nov 27 '18 at 13:18

7

You could map new objects with wanted properties and assign all to a single object.

const
    object = { abc: "Moon", def: "Earth", asd: "Sun", dmg: "Venus", xyz: "Mars", tuv: "Jupiter" },
    array = ["abc", "def", "tuv"],
    result = Object.assign(...array.map(k => ({ [k]: object[k] })));

console.log(result);

answered Nov 27 '18 at 13:18

Nina Scholz

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Thanks, is there any advantage over @mohammad-usman ’s approach? – Kalaschnik Nov 27 '18 at 13:23
it is just a different approach by generating single objects, instead of using a single object/accumulator of `reduce`. – Nina Scholz Nov 27 '18 at 13:28

Mohammad Usman · Answer 2 · 2018-11-27T13:21:07.173

6

You can use .reduce() to create the resultant object:

const arr = ["abc", "def", "tuv"];
const obj = {
    abc: "Moon",
    def: "Earth",
    asd: "Sun",
    dmg: "Venus",
    xyz: "Mars",
    tuv: "Jupiter"
};

const result = arr.reduce((r, c) => (r[c] = obj[c], r), {});

console.log(result);

edited Nov 27 '18 at 13:21

answered Nov 27 '18 at 13:16

Mohammad Usman

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Perfection! Could you briefly describe what the syntax does within the reduce()? – Kalaschnik Nov 27 '18 at 13:20
1

@Kalaschnik I've added a reference to the docs. It describes in detail how reduce works. – Mohammad Usman Nov 27 '18 at 13:21

Filter Object based on an array

2 Answers2