url decode in javascript with code examples

URL Decoding in JavaScript

URL encoding is the process of converting special characters in a URL into their encoded form. URL decoding is the reverse of URL encoding and it converts the encoded characters back into their original form. In this article, we will discuss URL decoding in JavaScript with code examples.

Why URL encoding is important?

URL encoding is important because URLs are limited to a specific set of characters, which are defined by the ASCII character set. ASCII is a 7-bit character set, which means that it can represent 128 different characters. But, some characters, such as spaces and punctuation, cannot be used in a URL. To overcome this limitation, the URL encoding technique is used, which converts these characters into their encoded form.

JavaScript provides several built-in functions to handle URL encoding and decoding, including encodeURI(), encodeURIComponent(), and decodeURI() and decodeURIComponent().

The encodeURI() function

The encodeURI() function is used to encode a complete URL, including all its components, such as the protocol, host, path, and query string. However, it does not encode characters that are considered safe, such as the following:

  • ASCII letters (A-Z, a-z)
  • Digits (0-9)
  • The characters: ; , / ? : @ & = + $ – _ . ! ~ * ' ( ) #

Here's an example of using the encodeURI() function:

let url = "https://www.example.com/search?q=javascript";
let encodedUrl = encodeURI(url);
// Output: https://www.example.com/search?q=javascript

The encodeURIComponent() function

The encodeURIComponent() function is used to encode individual components of a URL, such as the query string or path. It encodes all characters except for ASCII letters, digits, and the characters: – _ . ! ~ * ' ( ) .

Here's an example of using the encodeURIComponent() function:

let query = "javascript programming";
let encodedQuery = encodeURIComponent(query);
// Output: javascript%20programming

The decodeURI() function

The decodeURI() function is used to decode a complete URL that was previously encoded with the encodeURI() function.

Here's an example of using the decodeURI() function:

let encodedUrl = "https://www.example.com/search?q=javascript";
let decodedUrl = decodeURI(encodedUrl);
// Output: https://www.example.com/search?q=javascript

The decodeURIComponent() function

The decodeURIComponent() function is used to decode individual components of a URL that were previously encoded with the encodeURIComponent() function.

Here's an example of using the decodeURIComponent() function:

let encodedQuery = "javascript%20programming";
let decodedQuery = decodeURIComponent(encodedQuery);
// Output: javascript programming


In this article, we discussed URL decoding in JavaScript and covered the built-in functions for URL encoding and decoding. Understanding how to encode and decode URLs is essential for web development, as it helps you to build
Adjacent Topics to URL Decoding in JavaScript

  1. Query Strings: Query strings are a component of a URL that contain data to be passed to the server. They are used to send additional information to the server and are appended to the URL after a question mark (?). Query strings can be encoded using the encodeURIComponent() function, and decoded using the decodeURIComponent() function.

  2. JSON: JSON (JavaScript Object Notation) is a lightweight data-interchange format that is used to exchange data between a client and a server. It is a text-based format that is easy for humans to read and write and for machines to parse and generate. JSON is commonly used with APIs (Application Programming Interfaces) to send and receive data between a client and a server.

  3. HTTP Requests: HTTP (HyperText Transfer Protocol) requests are used to send data from a client to a server. The most common HTTP requests are GET, POST, PUT, and DELETE. GET requests are used to retrieve data from the server, POST requests are used to send data to the server, PUT requests are used to update data on the server, and DELETE requests are used to delete data on the server.

  4. Web Storage: Web storage is a client-side storage solution that allows you to store data on the client's device. There are two types of web storage, local storage, and session storage. Local storage is used to store data that should persist even after the user closes their browser, while session storage is used to store data that is only available for the duration of the user's session.

  5. Web APIs: Web APIs (Application Programming Interfaces) are used to allow clients to interact with servers and access data and functionality. Web APIs are typically accessed using HTTP requests and return data in a format such as JSON or XML. Web APIs are commonly used with web and mobile applications to allow clients to access data and functionality from a server.

  6. Cross-Site Scripting (XSS): Cross-Site Scripting is a security vulnerability that allows an attacker to inject malicious code into a web page viewed by other users. XSS attacks can be prevented by properly encoding user input before including it in a web page, and by using a Content Security Policy (CSP) to specify which sources of data are allowed to be executed on a web page.

In conclusion, URL decoding is just one aspect of web development, and it's essential to understand related topics such as query strings, JSON, HTTP requests, web storage, web APIs, and cross-site scripting to build robust and secure web applications.

Popular questions

  1. What is URL decoding in JavaScript?

URL decoding in JavaScript is the process of converting encoded data back into its original form. URL encoding is often used when sending data in a query string or in a POST request to ensure that the data is properly formatted for transmission. The JavaScript function decodeURIComponent() is used to perform URL decoding in JavaScript.

  1. What is the purpose of URL encoding?

URL encoding is used to encode special characters in a string of data so that it can be safely transmitted in a URL or as part of a query string. Special characters such as spaces, plus signs, and slashes can be encoded into a percent symbol followed by two hexadecimal characters. This ensures that the data is properly formatted and will not interfere with the transmission of the data.

  1. What is the syntax of the decodeURIComponent() function in JavaScript?

The syntax of the decodeURIComponent() function in JavaScript is as follows:


Where encodedURI is the string of encoded data that needs to be decoded. The function returns the decoded string.

  1. How can you use the decodeURIComponent() function to decode a query string in JavaScript?

To decode a query string in JavaScript, you can use the window.location.search property to retrieve the query string from the URL, and then pass it to the decodeURIComponent() function. For example:

var queryString = window.location.search;
var decodedQueryString = decodeURIComponent(queryString);
  1. Can you provide an example of URL decoding in JavaScript?

Yes, here is an example of URL decoding in JavaScript:

var encodedURI = "Hello%20World";
var decodedURI = decodeURIComponent(encodedURI);
console.log(decodedURI); // Output: Hello World

In this example, the encoded string "Hello%20World" is decoded using the decodeURIComponent() function, and the decoded string "Hello World" is logged to the console.



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