qs is a popular npm package used for serializing JavaScript objects into query strings. It provides an easy way to handle query parameters in web applications by converting object data into a format that can be appended to URLs for HTTP requests.

Prerequisites:

• Node.js and npm
• JavaScript

Features of npm qs

• Query String Serialization: It efficiently converts objects into query strings, handling nested objects, arrays, and various data types.
• Array Indexing: Supports array indices in query string serialization, ensuring accurate representation of array data.
• Customization: Offers options to customize serialization behaviour, such as array formatting and encoding.
• Parsing: Provides parsing uses to deserialize query strings back into JavaScript objects.

Steps to Create Application and Installing Package

Step 1: Create a new folder for your project in your terminal or command prompt.

mkdir qs-demo

Step 2: Navigate to the newly created folder.

cd qs-demo

Step 3: Initialize npm to create a package.json file.

npm init -y

Step 4: Install the qs package using npm.

npm install qs

Step 5: Create the index.js file.

Project Structure:

Folder Structure

Dependencies

"dependencies": {
    "qs": "^6.12.1"
}

Example 1: In this example, the qs package is used to serialize the data object into a query string using qs.stringify, which is then logged to the console. The serialized query string is then parsed back into an object using qs.parse.

//index.js

const qs = require('qs');
const data = {
    title: 'GeeksforGeeks',
    category: 'Programming',
    tags: ['JavaScript', 'Node.js', 'npm'],
};
const queryString = qs.stringify(data);
console.log('Serialized Query String:', queryString);
const res = qs.parse(queryString);
console.log('Parsed Data:', res);

Output:

qs.stringify

Example 2: In this example, the qs package is used to serialize the data object, including nested objects and arrays, into a query string with dot notation enabled (allowDots: true). The serialized query string is then parsed back into an object using qs.parse.

//index.js

const qs = require('qs');
const data = {
    title: 'GeeksforGeeks',
    details: {
        category: 'Programming',
        tags: ['JavaScript', 'Node.js', 'npm'],
    },
    author: {
        name: 'Sandeep Jain',
        age: 30,
    },
};
const queryString = qs.stringify(data, {
    allowDots: true
});
console.log('Serialized Query String:', queryString);
const res = qs.parse(queryString);
console.log('Parsed Data:', res);

Output:

serialize data object