Retrieve the value of a key by using the value of a different key within an object

Question

Retrieve the value of a key by using the value of a different key within an object

I often encounter a situation where I need to extract just an object key, rather than the entire object, based on another key value in the same object from an array of objects.

For instance, consider the following array of objects:

myArray = [
  {
    name: Person 1
    type: alpha
  },
  {
    name: Person 2
    type: beta
  },
  {
    name: Person 3
    type: gamma
  },
  {
    name: Person 4
    type: beta
  },
  {
    name: Person 5
    type: gamma
  },
];

If I want to retrieve only the name values for objects with a type of 'beta', how can I accomplish that? I am partial to lodash and familiar with using _.map or _.filter, such as:

var newArray = _.map(myArray, function(item) {
  return item.type === 'beta';
});

However, these methods return the entire object. I believe chaining may hold the solution, but I am struggling to identify how to achieve my desired outcome.

Thank you.

javascript arrays object lodash

Answer 1

Answer №1

If you want to achieve this, you can utilize the built-in Array.prototype.map() method. Here's an example using ES6 fat-arrow functions for brevity:

myArray.filter(item => item.type === 'beta').map(item => item.name)

For those who prefer the ES5 syntax, it would look like this:

myArray.filter(function(item) {return item.type === 'beta'})
     .map(function(item) {return item.name})

Answer 2

If you want to achieve this, you can utilize the built-in Array.prototype.map() method. Here's an example using ES6 fat-arrow functions for brevity:

myArray.filter(item => item.type === 'beta').map(item => item.name)

For those who prefer the ES5 syntax, it would look like this:

myArray.filter(function(item) {return item.type === 'beta'})
     .map(function(item) {return item.name})

Answer 3

Answer №2

This code snippet demonstrates how to use lodash's map and filter functions together.

var result = _(myArray).filter({ type: 'beta' }).map('name').value();

var myArray = [
  {
    name: 'Person 1',
    type: 'alpha'
  },
  {
    name: 'Person 2',
    type: 'beta'
  },
  {
    name: 'Person 3',
    type: 'gamma'
  },
  {
    name: 'Person 4',
    type: 'beta'
  },
  {
    name: 'Person 5',
    type: 'gamma'
  },
];

var result = _(myArray).filter({ type: 'beta' }).map('name').value();

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

Answer 4

This code snippet demonstrates how to use lodash's map and filter functions together.

var result = _(myArray).filter({ type: 'beta' }).map('name').value();

var myArray = [
  {
    name: 'Person 1',
    type: 'alpha'
  },
  {
    name: 'Person 2',
    type: 'beta'
  },
  {
    name: 'Person 3',
    type: 'gamma'
  },
  {
    name: 'Person 4',
    type: 'beta'
  },
  {
    name: 'Person 5',
    type: 'gamma'
  },
];

var result = _(myArray).filter({ type: 'beta' }).map('name').value();

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

Answer 5

Answer №3

If you want to extract only the names of items with type 'beta' from an array, you can achieve this by using the combination of filter and map methods:

myArray.
   filter(function(item){ return item.type === 'beta'; }).
   map(function(item){ return item.name; });

Answer 6

If you want to extract only the names of items with type 'beta' from an array, you can achieve this by using the combination of filter and map methods:

myArray.
   filter(function(item){ return item.type === 'beta'; }).
   map(function(item){ return item.name; });

Answer 7

Answer №4

Utilizing ES6 parameter destructuring:

myArray.filter(({type}) => type === 'beta').map(({name}) => name)

Answer 8

Utilizing ES6 parameter destructuring:

myArray.filter(({type}) => type === 'beta').map(({name}) => name)

Retrieve the value of a key by using the value of a different key within an object

Answer №1

Answer №2

Answer №3

Answer №4

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