Node.js URL.protocol API

The URL.protocol API in Node.js provides a way to parse and manipulate URLs. The protocol property in this API represents the protocol scheme of a URL, such as http, https, ftp, file, etc. In this article, we'll explore the URL.protocol API and see how it can be used in Node.js applications.

Syntax

The syntax for accessing the protocol property in the URL module of Node.js is as follows:

urlObject.protocol

Here, urlObject is the URL object created using the URL constructor. It represents the parsed URL string.

Examples

Let's take a look at some examples to understand how the URL.protocol API works.

Example 1: Getting Protocol

In this example, we'll see how to get the protocol of a given URL string using the URL.protocol property. Here's the code:

const url = require('url');

const urlString = 'https://www.example.com/';

const parsedUrl = new URL(urlString);

console.log(parsedUrl.protocol);

Output:

https:

Here, we first import the url module, which provides the URL constructor. We then define a URL string and create a new URL object using the URL constructor. Finally, we access the protocol property of the parsed URL object and print it to the console.

Example 2: Changing Protocol

In this example, we'll see how to change the protocol of a given URL string using the URL.protocol property. Here's the code:

const url = require('url');

const urlString = 'https://www.example.com/';

const parsedUrl = new URL(urlString);

parsedUrl.protocol = 'ftp:';

console.log(parsedUrl.toString());

Output:

ftp://www.example.com/

Here, we first import the url module and define a URL string. We then create a parsed URL object using the URL constructor. Next, we change the protocol of the parsed URL object to ftp. Finally, we print the updated URL string to the console using the toString() method of the parsed URL object.

Example 3: Error Handling

In this example, we'll see how error handling works when accessing the protocol property of a URL object. Here's the code:

const url = require('url');

const urlString = 'invalid-url';

try {
    const parsedUrl = new URL(urlString);
    console.log(parsedUrl.protocol);
} catch (err) {
    console.error(err);
}

Output:

TypeError [ERR_INVALID_URL]: Invalid URL: invalid-url
    at onParseError (internal/url.js:246:9)
    at new URL (internal/url.js:332:5)
    at Object.<anonymous> (/path/to/script.js:5:18)

Here, we define an invalid URL string and try to create a parsed URL object using the URL constructor. Since the URL string is invalid, this results in a TypeError with an error message indicating the URL is invalid. We handle this error using the try-catch block and print the error message to the console.

Conclusion

In this article, we explored the URL.protocol API in Node.js and saw how it can be used to parse and manipulate URLs. We looked at some examples of getting and changing the protocol of a URL, as well as error handling when accessing the protocol property. With this knowledge, you can now use the URL.protocol API to work with URLs in your Node.js applications.