Extract keys and values from object via an array of strings in javascript

Question

I have some api data that is being returned as an object:

    {
        "name": "Luke Skywalker",
        "height": "172",
        "mass": "77",
        "hair_color": "blond",
        "skin_color": "fair",
        "eye_color": "blue",
        "birth_year": "19BBY",
        "gender": "male"
}

I have a list of keys in a configuration array that I am interested to extract from the original response:

let attributes = ['name', 'height', 'mass'];

How do i use the attribute array to give me an object back like so:

{
        "name": "Luke Skywalker",
        "height": "172",
        "mass": "77"
}

Using destructuring you can get the values easily, as you know the names: let { name, height, mass } = objectWithTheseProperties; Or if you don't know if the object has the property in question you can use if (theObjectInQuestion.hasOwnProperty(propertyInQuestion)) { // do stuff }; — JDunken
– JDunken, Commented Feb 6, 2020 at 15:43

messerbill · Accepted Answer · 2020-02-06 15:40:23Z

2

You can just loop over your array:

const obj = {
        "name": "Luke Skywalker",
        "height": "172",
        "mass": "77",
        "hair_color": "blond",
        "skin_color": "fair",
        "eye_color": "blue",
        "birth_year": "19BBY",
        "gender": "male"
};

let attributes = ['name', 'height', 'mass'];

function buildObject(arr, obj) {
  const res = {};
  arr.forEach(item => res[item] = obj[item])
  return res
}

console.log(buildObject(attributes, obj))

answered Feb 6, 2020 at 15:40

messerbill

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Comments

Siva Kondapi Venkata · Accepted Answer · 2020-02-06 15:50:58Z

2

Using reduce will be simplified.

const update = (data, attrs) =>
  attrs.reduce((acc, attr) => (acc[attr] = data[attr], acc), {});

const data = {
  name: "Luke Skywalker",
  height: "172",
  mass: "77",
  hair_color: "blond",
  skin_color: "fair",
  eye_color: "blue",
  birth_year: "19BBY",
  gender: "male"
};

let attributes = ["name", "height", "mass"];

console.log(update(data, attributes));

answered Feb 6, 2020 at 15:50

Siva Kondapi Venkata

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Comments

Nina Scholz · Accepted Answer · 2020-02-06 15:48:48Z

1

You could map the wanted key along with their values and build a new object from it with Object.fromEntries.

let obj = { name: "Luke Skywalker", height: "172", mass: "77", hair_color: "blond", skin_color: "fair", eye_color: "blue", birth_year: "19BBY", gender: "male" },
    attributes = ['name', 'height', 'mass'],
    picked = Object.fromEntries(attributes.map(k => [k, obj[k]]));

console.log(picked);

answered Feb 6, 2020 at 15:48

Nina Scholz

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Comments

Mihai Alexandru-Ionut · Accepted Answer · 2020-02-06 15:54:20Z

1

You could use Object.entries method.

let obj = {
  "name": "Luke Skywalker",
  "height": "172",
  "mass": "77",
  "hair_color": "blond",
  "skin_color": "fair",
  "eye_color": "blue",
  "birth_year": "19BBY",
  "gender": "male"
};
let attributes = ['name', 'height', 'mass'];
let picked = Object.fromEntries(
  attributes.map(att => [att, obj[att]])
)
console.log(picked);

edited Feb 6, 2020 at 15:54

answered Feb 6, 2020 at 15:39

Mihai Alexandru-Ionut

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Comments

Ele · Accepted Answer · 2020-02-08 10:47:18Z

1

You can use the function reduce for building the desired object.

let obj = {"name": "Luke Skywalker","height": "172","mass": "77","hair_color": "blond","skin_color": "fair","eye_color": "blue","birth_year": "19BBY","gender": "male"},
    attributes = ['name', 'height', 'mass'],
    {result} = attributes.reduce((a, c) => (Object.assign(a.result, {[c]: a.source[c]}), a), {result: Object.create(null), source: obj});
    
console.log(result);

edited Feb 8, 2020 at 10:47

answered Feb 6, 2020 at 15:45

Ele

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