How to filter Nested Array using Key in JavaScript ?
Last Updated :
05 Feb, 2024
Filtering a nested array in JavaScript involves the process of selectively extracting elements from an array of objects, where each object contains another array. We will discuss how can we filter Nested Array using the key in JavaScript.
Filtering a nested array based on a key in JavaScript can be done using various methods:
Using filter method
The filter method is used to filter the main array based on a condition specified using the same method. The same method checks if at least one element in the nested array meets the given condition. This method directly filters the objects in the main array based on the specified key and value.
Example: This example shows the filtering of a nested array using the key by using the filter method.
JavaScript
// data taken
const data = [
{
id: 1, items: [{ name: 'item1' },
{ name: 'item2' }]
},
{
id: 2, items: [{ name: 'item3' },
{ name: 'item4' }]
},
{
id: 3, items: [{ name: 'item5' },
{ name: 'item6' }]
}
];
const keyToFilter = 'name';
const valueToFilter = 'item3';
const filteredData = data.filter(obj =>
obj.items.some(item => item[keyToFilter] === valueToFilter));
console.log(JSON.stringify(filteredData, null, 2));
Output[
{
"id": 2,
"items": [
{
"name": "item3"
},
{
"name": "item4"
}
]
}
]
Using reduce method
The reduce() method is applied in this approach to iteratively build a new array that contains only the objects meeting the specified condition. The filter method is used to filter the items in the nested array, and the result is added to the accumulator array.
Example: This example shows the filtering of nested array using the key by using the reduce method.
JavaScript
const data = [
{ id: 1, items: [{ name: 'item1' }, { name: 'item2' }] },
{ id: 2, items: [{ name: 'item3' }, { name: 'item4' }] },
{ id: 3, items: [{ name: 'item5' }, { name: 'item6' }] }
];
const keyToFilter = 'name';
const valueToFilter = 'item3';
const filteredData = data.reduce((acc, obj) => {
const filteredItems = obj.items.filter(item => item[keyToFilter] === valueToFilter);
if (filteredItems.length > 0) {
acc.push({ ...obj, items: filteredItems });
}
return acc;
}, []);
console.log(JSON.stringify(filteredData, null, 2));
Output[
{
"id": 2,
"items": [
{
"name": "item3"
}
]
}
]
Using map and filter
The map and filter methods to achieve the desired result. First, the map method is used to iterate over each object in the main array. Then, the filter method is applied to the nested array within each object, isolating only the items that match the specified key and value.
Example: This example shows the filtering of a nested array using the key by using the map and filter method.
JavaScript
const data = [
{ id: 1, items: [{ name: 'item1' }, { name: 'item2' }] },
{ id: 2, items: [{ name: 'item3' }, { name: 'item4' }] },
{ id: 3, items: [{ name: 'item5' }, { name: 'item6' }] }
];
const keyToFilter = 'name';
const valueToFilter = 'item3';
const filteredData = data.map(obj => ({
...obj,
items: obj.items.filter(item => item[keyToFilter] === valueToFilter)
})).filter(obj => obj.items.length > 0);
console.log(JSON.stringify(filteredData, null, 2));
Output[
{
"id": 2,
"items": [
{
"name": "item3"
}
]
}
]
Similar Reads
Non-linear Components In electrical circuits, Non-linear Components are electronic devices that need an external power source to operate actively. Non-Linear Components are those that are changed with respect to the voltage and current. Elements that do not follow ohm's law are called Non-linear Components. Non-linear Co
11 min read
JavaScript Tutorial JavaScript is a programming language used to create dynamic content for websites. It is a lightweight, cross-platform, and single-threaded programming language. It's an interpreted language that executes code line by line, providing more flexibility.JavaScript on Client Side: On the client side, Jav
11 min read
Web Development Web development is the process of creating, building, and maintaining websites and web applications. It involves everything from web design to programming and database management. Web development is generally divided into three core areas: Frontend Development, Backend Development, and Full Stack De
5 min read
Spring Boot Tutorial Spring Boot is a Java framework that makes it easier to create and run Java applications. It simplifies the configuration and setup process, allowing developers to focus more on writing code for their applications. This Spring Boot Tutorial is a comprehensive guide that covers both basic and advance
10 min read
React Interview Questions and Answers React is an efficient, flexible, and open-source JavaScript library that allows developers to create simple, fast, and scalable web applications. Jordan Walke, a software engineer who was working for Facebook, created React. Developers with a JavaScript background can easily develop web applications
15+ min read
React Tutorial React is a powerful JavaScript library for building fast, scalable front-end applications. Created by Facebook, it's known for its component-based structure, single-page applications (SPAs), and virtual DOM,enabling efficient UI updates and a seamless user experience.Note: The latest stable version
7 min read
JavaScript Interview Questions and Answers JavaScript is the most used programming language for developing websites, web servers, mobile applications, and many other platforms. In Both Front-end and Back-end Interviews, JavaScript was asked, and its difficulty depends upon the on your profile and company. Here, we compiled 70+ JS Interview q
15+ min read
Class Diagram | Unified Modeling Language (UML) A UML class diagram is a visual tool that represents the structure of a system by showing its classes, attributes, methods, and the relationships between them. It helps everyone involved in a projectâlike developers and designersâunderstand how the system is organized and how its components interact
12 min read
Backpropagation in Neural Network Back Propagation is also known as "Backward Propagation of Errors" is a method used to train neural network . Its goal is to reduce the difference between the modelâs predicted output and the actual output by adjusting the weights and biases in the network.It works iteratively to adjust weights and
9 min read
3-Phase Inverter An inverter is a fundamental electrical device designed primarily for the conversion of direct current into alternating current . This versatile device , also known as a variable frequency drive , plays a vital role in a wide range of applications , including variable frequency drives and high power
13 min read