Convert array into specific object

Question

Given the following JSON

{
gif: ['small', 'medium', 'large'],
jpeg: ['tiny', 'huge']
}

I would like to convert each element in the array into a key in a sub object and assign it to it a quantity of 1.

As such

{
gif: {
  small: {quantity: 1},
  medium: {quantity: 1},
  large: {quantity:1}
  },
jpeg: {
  tiny: {quantity:1},
  huge: {quantity: 1}
  }
}

The closest I've come is with the following

for(let image in obj) { 
  obj[image].forEach(size => { obj[image][size] = { quantity:1}})
}

However unfortunately this out puts

{ gif: 
  [ 'small',
    'medium',
    'large',
     small: {quantity: 1},
     medium: {quantity: 1},
     large: {quantity: 1} ],
 jpeg: [ 'huge', 'tiny', tiny: {quantity:1} huge: {quantity: 1 } ] 
}

Any help would be awesome, thanks

Kosh · Accepted Answer · 2018-02-17 01:34:29Z

4

You can convert it in-place using reduce within forEach loop:

const o = {
  gif: ['small', 'medium', 'large'],
  jpeg: ['tiny', 'huge']
}

Object.keys(o)
  .forEach(
    k => o[k] = o[k].reduce(
      (a, e) => (a[e] = {
        quantity: 1
      }) && a, {}
    )
  )

console.log(o)

And convert into a new object using double reduce:

const o = {
  gif: ['small', 'medium', 'large'],
  jpeg: ['tiny', 'huge']
}

var o2 = Object.keys(o).reduce((n, k) => (n[k] = o[k].reduce((a, e) => (a[e] = {quantity:1}) && a, {})) && n, {})

console.log(o2)

edited Feb 17, 2018 at 1:34

answered Feb 17, 2018 at 1:06

Kosh

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1 Comment

RaphaMex Over a year ago

&& a seems nice. Is it safe? I would have done an Object.assign() instead.

iLyas · Accepted Answer · 2018-02-17 02:04:47Z

1

You can use the .reduce() method

const obj = {
  gif: ['small', 'medium', 'large'],
  jpeg: ['tiny', 'huge']
};


for (let image in obj) {
  obj[image] = obj[image].reduce((result, item) => {
    result[item] = {
      quantity: 1
    };
    return result;
  }, {});
}

console.log(obj);

edited Feb 17, 2018 at 2:04

answered Feb 17, 2018 at 1:58

iLyas

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2 Comments

Verric Over a year ago

While, all the other current solutions also work, and I'm aware the for ...let syntax is the same as Object.keys, this one one looks the simplest and easiest to read in IMHO. Thanks

Lennholm Over a year ago

@Verric in is NOT the same as Object.keys(). in has a very big caveat that you need to be aware of: that is that it includes properties from the prototype chain, which is normally not something you want when iterating over an object's properties.

Nenad Vracar · Accepted Answer · 2018-02-17 01:08:49Z

0

You can use reduce method on Object.keys and inside you can use map and Object.assign to return new object.

const data = {
  gif: ['small', 'medium', 'large'],
  jpeg: ['tiny', 'huge']
}

const result = Object.keys(data).reduce(function(r, e) {
  r[e] = Object.assign({}, ...data[e].map(k => ({[k]: {quantity: 1}})))
  return r;
}, {})
console.log(result)

answered Feb 17, 2018 at 1:08

Nenad Vracar

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Comments

Pavlo · Accepted Answer · 2018-02-17 01:12:12Z

0

const obj = {
  gif: ['small', 'medium', 'large'],
  jpeg: ['tiny', 'huge']
}

const objKeys = Object.keys(obj);

for(let i=0;i<objKeys.length;i++){
  const currentKey = objKeys[i];
  obj[currentKey] = obj[currentKey].reduce((sum, element) => { 
    sum[element] = {quantity: 1};
    return sum;
  }, {});
}

This is one solution, you go through the array and replace it with objects

answered Feb 17, 2018 at 1:12

Pavlo

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