CODEWITHSUNDEEP
javascriptjsonkey-value
user1837293
user1837293

Reputation: 1676

How retrieve json element by key (Javascript)

I would like to retrieve option with key '2021-05-14' from this json-object.

{
  stock: {
    zip: '95014',
    lastUpdated: '05/02/2021'
  },
  options: [
    { '2021-05-07': [Object] },
    { '2021-05-14': [Object] },
    { '2021-05-21': [Object] },
    { '2021-05-28': [Object] },
    { '2021-06-04': [Object] },
    { '2021-06-18': [Object] }
  ]
}

I tried:

var options;
var expirationSeries;
options = res.body.options;  // res.body is the json-object
for (var key in options)
{
  if (key=='2021-05-14') {
    expirationSeries = options[key];
  };
}
console.log(expirationSeries);

but then I get error 'undefined'.

How to do this properly?

Upvotes: 0

Views: 1164

Answers (5)

adiga
adiga

Reputation: 35259

Using for (var key in options) over an array will assign the indices of the array to key variable.

You could use for..of loop and use hasOwnProperty to check if the object has that date as property. Since you want only one match, you could break if a match is found

for (const o of options) {
  if (o.hasOwnProperty('2021-05-14')) {
    expirationSeries = o
    break;
  }
}

Here's a snippet:

let options = [{"2021-05-07":{foo:"bar"}},{"2021-05-14":{foo:"bar"}},{"2021-05-21":{foo:"bar"}},{"2021-05-28":{foo:"bar"}},{"2021-06-04":{foo:"bar"}},{"2021-06-18":{foo:"bar"}}],
    expirationSeries;
  
for (const o of options) {
  if (o.hasOwnProperty('2021-05-14')) {
    expirationSeries = o
    break;
  }
}

console.log(expirationSeries)

You could use find and hasOwnProperty to get the object which has the specified key. If multiple objects can have that key, use filter to get all the matches

const expirationSeries = options.find(a => a.hasOwnProperty('2021-05-21'))
const allMatches = options.filter(a => a.hasOwnProperty('2021-05-21'))

Here's a snippet:

const options = [{"2021-05-07":{foo:"bar"}},{"2021-05-14":{foo:"bar"}},{"2021-05-21":{foo:"bar"}},{"2021-05-28":{foo:"bar"}},{"2021-06-04":{foo:"bar"}},{"2021-06-18":{foo:"bar"}}],
    expirationSeries = options.find(a => a.hasOwnProperty('2021-05-21')),
    allMatches = options.filter(a => a.hasOwnProperty('2021-05-21'))

console.log(expirationSeries)
console.log(allMatches)

Upvotes: 1

Mamun
Mamun

Reputation: 68933

Instead of for...in you can try using for...of.

Demo:

var options;
var expirationSeries;
options = [
    { '2021-05-07': 'data 1' },
    { '2021-05-14': 'data 2' },
    { '2021-05-21': 'data 3' },
    { '2021-05-28': 'data 4' },
    { '2021-06-04': 'data 5' },
    { '2021-06-18': 'data 6' }
  ]
for (var obj of options)
{
  var k = Object.keys(obj)[0];
  if (k=='2021-05-14') {
    expirationSeries = obj[k];
  };
}
console.log(expirationSeries);

OR: You can try using .find()

var options = [
    { '2021-05-07': 'data 1' },
    { '2021-05-14': 'data 2' },
    { '2021-05-21': 'data 3' },
    { '2021-05-28': 'data 4' },
    { '2021-06-04': 'data 5' },
    { '2021-06-18': 'data 6' }
  ];
var temp = options.find(o => Object.keys(o)[0] === '2021-05-14');
var expirationSeries =  temp != undefined ? Object.values(temp)[0] : 'not found';
console.log(expirationSeries);

Upvotes: 1

KooiInc
KooiInc

Reputation: 123016

You can use Array.find to find the object within the options array. Something like:

const fromJson = {
  stock: {
    zip: '95014',
    lastUpdated: '05/02/2021'
  },
  options: [
    { '2021-05-07': {} },
    { '2021-05-14': {} },
    { '2021-05-21': {} },
    { '2021-05-28': {} },
    { '2021-06-04': {} },
    { '2021-06-18': {} },
  ]
}

const expirationSeries = findOptionByKey(`2021-05-14`);
console.log(expirationSeries);

// not found
console.log(findOptionByKey(`2022-03-12`));


function findOptionByKey(key2Find) {
  const keyFinder = obj => obj[key2Find];
  return fromJson.options.find(keyFinder) || `option [${key2Find}] not found`;
}

Upvotes: 1

AnthonyTonev
AnthonyTonev

Reputation: 21

Since options is an array you can use find to get the first object that has a property key in it.

const jsonData = {
  stock: {
    zip: '95014',
    lastUpdated: '05/02/2021'
  },
  options: [
    { '2021-05-07': {} },
    { '2021-05-14': {} },
    { '2021-05-21': {} },
    { '2021-05-28': {} },
    { '2021-06-04': {} },
    { '2021-06-18': {} }
  ]
 }

const key = '2021-05-21';

const result = jsonData.options.find(option => key in option );

console.log(result)

Upvotes: 2

benada002
benada002

Reputation: 281

You could also try this:

options.forEach(obj => {
  const key = Object.keys(obj)[0];

  if (key == '2021-05-14') {
    expirationSeries = options[key];
  };
});

Upvotes: 1

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