Ways to retrieve both keys and values from an array efficiently using array functions

Question

Ways to retrieve both keys and values from an array efficiently using array functions

Given the following array:

const school = [
  { Students: 4, Teachers: 15, Department: 'Mathematics' },
  { Students: 4, Teachers: 15, Department: 'English' },
  { Students: 4, Teachers: 15, Department: 'Science'} 
]

I am interested in retrieving all values associated with a specific key:

const students = [
  { Students: 4 },
  { Students: 4 },
  { Students: 4 }
]

Instead of using a for in loop, is there a way to achieve this utilizing methods like map, filter, find, or reduce? I have been struggling to extract the key value.

Solution:

school.map(data => `Students: ${data.Students}`);

You can encapsulate this functionality within a function:

getByKey(arr, val) {
    arr.map(data => `${val}: ${data[val]}`);
}


getKey(school, Department)

javascript arrays filter find maps

Answer 1

Answer №1

To simplify the process, focus on extracting information related to Students only by utilizing map method.

const university = [{
  Students: 46,
  Lecturers: 2,
  Faculty: 'Mathematics'
}, {
  Students: 65,
  Lecturers: 6,
  Faculty: 'English'
}, {
  Students: 48,
  Lecturers: 4,
  Faculty: 'Science'
}]

let result = [];

result = university.map(obj => {
  return {
    Students: obj.Students
  }
});

console.log(result)

Answer 2

To simplify the process, focus on extracting information related to Students only by utilizing map method.

const university = [{
  Students: 46,
  Lecturers: 2,
  Faculty: 'Mathematics'
}, {
  Students: 65,
  Lecturers: 6,
  Faculty: 'English'
}, {
  Students: 48,
  Lecturers: 4,
  Faculty: 'Science'
}]

let result = [];

result = university.map(obj => {
  return {
    Students: obj.Students
  }
});

console.log(result)

Answer 3

Answer №2

To extract specific keys from an array of objects, you can utilize the map function along with fromEntries to create a new object containing only the desired keys.

const data = 
  [ { Name: 'Alice', Age: 25, Country: 'USA' }, { Name: 'Bob', Age: 30, Country: 'Canada'} , { Name: 'Eve', Age: 22, Country: 'UK' } ];
  
const selectKeys=(arr,keys)=> arr.map(obj=>Object.fromEntries(keys.map(key=>[key,obj[key]])));

console.log(selectKeys(data, ['Name', 'Country']));
console.log(selectKeys(data, ['Age']));

Answer 4

To extract specific keys from an array of objects, you can utilize the map function along with fromEntries to create a new object containing only the desired keys.

const data = 
  [ { Name: 'Alice', Age: 25, Country: 'USA' }, { Name: 'Bob', Age: 30, Country: 'Canada'} , { Name: 'Eve', Age: 22, Country: 'UK' } ];
  
const selectKeys=(arr,keys)=> arr.map(obj=>Object.fromEntries(keys.map(key=>[key,obj[key]])));

console.log(selectKeys(data, ['Name', 'Country']));
console.log(selectKeys(data, ['Age']));

Answer 5

Answer №3

A neat and efficient way to achieve this is by utilizing the map() function:

const classes = school.map(function(s){
    return {"Classes" : s.Classes};
});

Answer 6

A neat and efficient way to achieve this is by utilizing the map() function:

const classes = school.map(function(s){
    return {"Classes" : s.Classes};
});

Answer 7

Answer №4

Employing the map function, all without utilizing the return keyword:

college.map(college=>({Graduates:college.Graduates}));

Answer 8

Employing the map function, all without utilizing the return keyword:

college.map(college=>({Graduates:college.Graduates}));

Ways to retrieve both keys and values from an array efficiently using array functions

Answer №1

Answer №2

Answer №3

Answer №4

Similar questions

Display the child elements in an HTML document that have the same class name as the parent element, while concealing all

Tips for developing integration tests for medium-sized nodejs applications with heavy reliance on 3rd party APIs

Differences between addEventListener and jQuery's on method, as well as form.submit and jQuery's

Customize time formatting in Angular to accommodate localized time formats

Having Trouble with Bootstrap 4 JQuery Responsive Tabs? Check out the provided code snippet for a solution

Saving multiple instances of an object using Mongoose

Table expands to full width

use ajax to post saved data to a WebAPI in php

Learn how to utilize Javascript to easily drag and drop an image within the same block

Custom options titled MUI Palette - The property 'primary' is not found in the 'TypeBackground' type

Refreshing the state when making changes to ng-repeat through orderBy and/or filter

A guide on extracting the value of a key from an object in angularjs

Discover how to retrieve service response data from an API and populate it into the Select Option with Angular 2

Having Trouble with Jquery UI Date Picker?

Creating a single submit handler for multiple forms in React

The functionality to remove table rows when checkboxes are selected is not functioning as expected in an Angular 7 application

Receiving a null result when parsing a JSON file from a URL in JavaScript

fill collections within backbone

Angular Ordering Map Object

What is the best way to display time instead of angles in highcharts?