JS/ES6: How to get specific fields of object array and return a single object with specific value?

Question

There is an object array like this:

const schema = [
    { placeholder: 'Title', name: 'title' },
    { placeholder: 'Authors', name: 'author' },
    { placeholder: 'Publisher',  name: 'publisher', optional: true },
    { placeholder: 'Edition', name: 'edition', optional: true }
]

Now I would like to get an object with all name fields as key with 1 value:

result = { 'title': 1, 'author': 1, 'publisher': 1, 'edition': 1 }

I tried to use map, but

schema.map(o => { return o.name })

gives me just an array:

['title', 'author', 'publisher', 'edition']

Yury Tarabanko · Accepted Answer · 2017-06-19 11:54:23Z

5

You need reduce

const schema = [
    { placeholder: 'Title', name: 'title' },
    { placeholder: 'Authors', name: 'author' },
    { placeholder: 'Publisher',  name: 'publisher', optional: true },
    { placeholder: 'Edition', name: 'edition', optional: true }
]

console.log(schema.reduce((acc, {name}) => (acc[name] = 1, acc), {}))

answered Jun 19, 2017 at 11:54

Yury Tarabanko

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Comments

Erazihel · Accepted Answer · 2017-06-19 11:54:27Z

3

const schema = [
    { placeholder: 'Title', name: 'title' },
    { placeholder: 'Authors', name: 'author' },
    { placeholder: 'Publisher',  name: 'publisher', optional: true },
    { placeholder: 'Edition', name: 'edition', optional: true }
];

console.log(schema.reduce((acc, current) => {
  acc[current.name] = 1;
  
  return acc;
}, {}));

answered Jun 19, 2017 at 11:54

Erazihel

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Comments

trincot · Accepted Answer · 2017-06-19 11:58:44Z

3

You could use Object.assign and the spread syntax:

Object.assign(...schema.map(o => ({ [o.name]: 1 })));

const schema = [
    { placeholder: 'Title', name: 'title' },
    { placeholder: 'Authors', name: 'author' },
    { placeholder: 'Publisher',  name: 'publisher', optional: true },
    { placeholder: 'Edition', name: 'edition', optional: true }
];

const result = Object.assign(...schema.map(o => ({ [o.name]: 1 })));
console.log(result);

answered Jun 19, 2017 at 11:58

trincot

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2 Comments

Yury Tarabanko Over a year ago

The most ESNexty answer :)

trincot Over a year ago

@YuryTarabanko, thanks for the appreciation, but strictly speaking this only uses ES2015 features (Object.assign, ..., =>, object literals with dynamic property names).

Nenad Vracar · Accepted Answer · 2017-06-19 11:54:42Z

1

You can first create an object and the use forEach loop to add properties.

const schema = [
  { placeholder: 'Title', name: 'title' },
  { placeholder: 'Authors', name: 'author' },
  { placeholder: 'Publisher',  name: 'publisher', optional: true },
  { placeholder: 'Edition', name: 'edition', optional: true }
]

var obj = {}
schema.forEach(o => obj[o.name] = 1)
console.log(obj)

answered Jun 19, 2017 at 11:54

Nenad Vracar

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Comments

AdityaParab · Accepted Answer · 2017-06-19 11:54:36Z

0

.map will always give you an array. Since you want to convert you array of objects to single object, it makes sense to use .reduce instead.

schema.reduce( (a, c) => {
  a[c.name] = 1;
  return a;
} , {});

answered Jun 19, 2017 at 11:54

AdityaParab

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