I am currently unsure of how to retrieve the value of a particular key within a JavaScript map that contains multiple sets of data

Question

I am currently unsure of how to retrieve the value of a particular key within a JavaScript map that contains multiple sets of data

I am working with a JavaScript map that contains multiple values. Here is an example (simplified for clarity):

Map(2) { 
  'group1' => {
    username: 'userTest',
    dsId: '710300636817653790',
    openDate: '2021-12-13 18:29:16'
 },
  'group2' => {
    username: 'Juojo',
    dsId: '477581625841156106',
    openDate: '2021-12-13 18:29:23'
 }
}

My goal is to retrieve the username value ('Juojo') from the second group of data. I attempted to do this:

console.log(map.get(group2.username));

However, this returns "undefined". When I try without the ".username" (console.log(map.get(group2));), it gives me:

{
  username: 'Juojo',
  dsId: '477581625841156106',
  openDate: '2021-12-13 18:29:23'
}

I only want the output to be "Juojo"

javascript maps

Answer 1

Answer №1

Retrieve the username attribute from the object fetched using the fetch method.

console.log(map.fetch(group2).username);

If there is a possibility that the key may not be present, you have the option to utilize the optional chaining operator, which will result in undefined instead of throwing an error.

console.log(map.fetch(group2)?.username);

Answer 2

Retrieve the username attribute from the object fetched using the fetch method.

console.log(map.fetch(group2).username);

If there is a possibility that the key may not be present, you have the option to utilize the optional chaining operator, which will result in undefined instead of throwing an error.

console.log(map.fetch(group2)?.username);

Answer 3

Answer №2

To access the object stored in your map, you can retrieve it and then read its properties as shown in the example below:

const myMap = new Map([ 
  ['group1',{
    username: 'userTest',
    dsId: '710300636817653790',
    openDate: '2021-12-13 18:29:16'
 }],
  ['group2', {
    username: 'Juojo',
    dsId: '477581625841156106',
    openDate: '2021-12-13 18:29:23'
 }]
])

const userName = myMap.get('group2').username;

console.log(userName);

Answer 4

To access the object stored in your map, you can retrieve it and then read its properties as shown in the example below:

const myMap = new Map([ 
  ['group1',{
    username: 'userTest',
    dsId: '710300636817653790',
    openDate: '2021-12-13 18:29:16'
 }],
  ['group2', {
    username: 'Juojo',
    dsId: '477581625841156106',
    openDate: '2021-12-13 18:29:23'
 }]
])

const userName = myMap.get('group2').username;

console.log(userName);

I am currently unsure of how to retrieve the value of a particular key within a JavaScript map that contains multiple sets of data

Answer №1

Answer №2

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