Node.js | URLSearchParams.forEach()

Introduction

Node.js provides a built-in module called "URLSearchParams" for working with URL query strings. The "URLSearchParams" class represents a collection of key-value pairs that can be used for constructing or parsing query strings.

The URLSearchParams.forEach() method is one of the several methods provided by this class. It allows you to iterate over all the name-value pairs in a "URLSearchParams" object and perform some operation on them. In this article, we will explore the details of this method and explain how to use it in your Node.js applications.

Syntax

The basic syntax of the URLSearchParams.forEach() method is as follows:

URLSearchParams.forEach(callback[, thisArg])

Here, "callback" is the function that will be called for each name-value pair in the "URLSearchParams" object. The "thisArg" parameter is an optional argument that can be used to set the this binding inside the callback function.

Parameters

The URLSearchParams.forEach() method takes two parameters:

callback

This is the function that will be called for each name-value pair in the "URLSearchParams" object. The callback function takes the following parameters:

• value: The value of the current name-value pair.

• name: The name of the current name-value pair.

• searchParams: The "URLSearchParams" object that the current pair belongs to.

The callback function can be an arrow function or a regular function. It can also have additional parameters after the required parameters listed above.

thisArg (optional)

This is the object to use as this when executing the "callback" function. If not provided, the global object will be used.

Return value

The URLSearchParams.forEach() method does not return anything. It is used for performing some operation on each name-value pair in the "URLSearchParams" object.

Example usage

Case 1: Simple Usage

const searchParams = new URLSearchParams('foo=1&bar=2');

searchParams.forEach((value, name, searchParams) => {
  console.log(`${name} = ${value}`);
});

Output:

foo = 1
bar = 2

In the above example, we created a new "URLSearchParams" object with the query string foo=1&bar=2. We then called the forEach() method on this object and passed a callback function that simply logs the name and value of each name-value pair to the console.

Case 2: Using "thisArg"

const searchParams = new URLSearchParams('foo=1&bar=2');
const obj = { count: 0 };

searchParams.forEach(function(value, name, searchParams) {
  this.count++;
}, obj);

console.log(obj.count); // 2

In the above example, we created a new "URLSearchParams" object with the query string foo=1&bar=2. We also created an object "obj" with a count property initialized to 0. We then called the forEach() method on the "URLSearchParams" object, passing a callback function that increments the count property of the "obj" object by 1 for each name-value pair in the object. We passed the "obj" object as the second argument to the forEach() method to set the this binding for the callback function.

Conclusion

The URLSearchParams.forEach() method is a powerful method provided by Node.js that makes it easy to manipulate query strings in your applications. By using this method, you can iterate over all the name-value pairs in a "URLSearchParams" object and perform some operation on each pair. Use the forEach() method to simplify your code and save time.