Extracting Domain Name without Subdomain using JavaScript

Introduction

Extracting the domain name without the subdomain from a URL is an important task in web development and data analysis. It allows us to focus on the main website or domain and disregard any subdomains that may be present. This can be useful in various scenarios such as identifying the source of website traffic or analyzing user behavior on a specific domain.

In this blog post, we will explore different methods for extracting the domain name without the subdomain using JavaScript. We will discuss the advantages and disadvantages of each method and provide practical examples to illustrate their implementation. By the end of this article, you will have a clear understanding of how to extract the domain name without the subdomain from a URL using JavaScript.

Understanding URLs

A URL (Uniform Resource Locator) is a string of characters that is used to address and access resources on the internet. It consists of several components, including the protocol, subdomain, domain, and path.

The protocol specifies the rules and conventions for communication between the client (browser) and the server. Common protocols include HTTP (Hypertext Transfer Protocol) and HTTPS (HTTP Secure).

The subdomain is an optional part of a URL that precedes the domain. It is often used to categorize or organize different sections or services of a website. For example, in the URL "https://blog.example.com/article", the subdomain is "blog".

The domain is the main part of a URL and represents the address of a website. It typically consists of two or more parts separated by dots. In the example URL mentioned earlier, the domain is "example.com".

The path is an optional part of a URL that comes after the domain and is used to specify a specific resource or page on the website. In our example URL, the path is "/article".

Extracting the domain name without the subdomain is important in many cases. It allows us to focus on the main domain of a website, which can be useful for various purposes such as tracking analytics, enforcing security policies, or performing URL-based operations. By removing the subdomain, we can obtain a cleaner and more standardized representation of the domain.

Methods for Extracting the Domain Name

There are multiple methods available to extract the domain name without the subdomain from a URL using JavaScript. In this section, we will explore two commonly used methods: using the window.location object and using regular expressions.

Method 1: Using the window.location Object

The window.location object provides information about the current URL in the browser window. It contains properties such as href, protocol, hostname, pathname, etc. To extract the domain name without the subdomain, we can simply access the hostname property of the window.location object.

Here's an example of how to implement this method in JavaScript:

function extractDomainFromUrl() {
  var domain = window.location.hostname;
  var parts = domain.split('.');
  var topLevelDomain = parts[parts.length - 1];

  // Check if the domain has a subdomain
  if (parts.length > 2) {
    domain = parts.slice(parts.length - 2).join('.');
  }

  return domain;
}

var domainName = extractDomainFromUrl();
console.log(domainName);

Method 2: Using Regular Expressions

Regular expressions provide a powerful way to search, match, and manipulate strings. We can use regular expressions to extract the domain name without the subdomain from a URL.

Here's an example of how to implement this method in JavaScript:

function extractDomainFromUrl() {
  var url = window.location.href;
  var domain = url.match(/^(?:https?:\/\/)?(?:[^@\n]+@)?(?:www\.)?([^:\/\n]+)/im)[1];
  
  return domain;
}

var domainName = extractDomainFromUrl();
console.log(domainName);

In this example, the regular expression /^(?:https?:\/\/)?(?:[^@\n]+@)?(?:www\.)?([^:\/\n]+)/im is used to match the domain name without the subdomain from the URL.

Comparison of Methods

Both methods have their own advantages and disadvantages.

Using the window.location object is straightforward and easy to implement. It doesn't require any additional libraries or complex regular expressions. However, it may not work in situations where the JavaScript code is executed in a different context or environment.

On the other hand, using regular expressions provides more flexibility and control over the extraction process. It can be useful when dealing with complex URLs or when the window.location object is not accessible. However, regular expressions can be more difficult to understand and maintain, especially for developers who are not familiar with them.

When choosing the appropriate method, consider factors such as the context in which the code will be executed, the complexity of the URLs being processed, and the familiarity of the development team with regular expressions.

In the next section, we will provide practical examples of how to extract the domain name without the subdomain using both methods.

Method 1: Using the window.location Object

The window.location object in JavaScript provides information about the current URL of the webpage. This object contains various properties, including hostname, which represents the domain name.

To extract the domain name without the subdomain using the window.location object, we can implement a custom JavaScript function. Here is an example:

function extractDomainFromURL(url) {
  var hostname;
  
  // If the URL starts with "http://" or "https://", remove it
  if (url.indexOf('http://') === 0 || url.indexOf('https://') === 0) {
    url = url.replace(/^(http:\/\/|https:\/\/)/, '');
  }
  
  // Use the window.location object to extract the domain name
  var parser = document.createElement('a');
  parser.href = url;
  hostname = parser.hostname;
  
  // Remove the subdomain from the domain name
  var parts = hostname.split('.');
  if (parts.length > 2) {
    hostname = parts.slice(1).join('.');
  }
  
  return hostname;
}

// Usage example
var url = 'https://www.example.com/some-page';
var domain = extractDomainFromURL(url);
console.log(domain); // Output: example.com

In this example, the extractDomainFromURL function takes a URL as its parameter and returns the extracted domain name without the subdomain. The function first checks if the URL starts with "http://" or "https://", and if so, it removes it. Then, it uses the window.location object to extract the hostname from the URL. Finally, it removes the subdomain from the hostname, if present, and returns the resulting domain name.

By using the window.location object, we can easily extract the domain name without the subdomain from a URL in JavaScript. This method is straightforward and does not require any external dependencies.

Method 2: Using Regular Expressions

Regular expressions are a powerful tool for pattern matching and extracting specific information from strings. In the context of extracting the domain name without the subdomain from a URL, regular expressions can be used to match and capture the desired part of the URL.

To implement a custom JavaScript function using regular expressions to extract the domain name without the subdomain, follow these steps:

1. Initialize a regular expression pattern that matches the desired part of the URL. The pattern should match the protocol (optional), followed by the subdomain (optional), followed by the domain name, and any characters after the domain name (e.g., path or query parameters). Here is an example pattern: /^(?:https?:\/\/)?(?:[^@\n]+@)?(?:www\.)?([^:\/\n]+)/im.

2. Create a JavaScript function that takes a URL as input.

3. Inside the function, use the match() method of the URL string with the regular expression pattern as an argument. This method returns an array of matches.

4. Access the desired part of the URL by accessing the first captured group from the match result. In this case, it would be the domain name without the subdomain.

5. Return the extracted domain name.

Here is an example implementation of a custom JavaScript function using regular expressions to extract the domain name without the subdomain:

function extractDomainName(url) {
  const pattern = /^(?:https?:\/\/)?(?:[^@\n]+@)?(?:www\.)?([^:\/\n]+)/im;
  const matches = url.match(pattern);
  if (matches && matches.length > 1) {
    return matches[1];
  }
  return null;
}

// Example usage
const url = "https://www.example.com/path/to/page";
const domainName = extractDomainName(url);
console.log(domainName); // Output: example.com

By using regular expressions, we can create a flexible and customizable solution to extract the domain name without the subdomain from a URL. Regular expressions provide a robust way to handle different URL formats and variations.

Comparison of Methods

When it comes to extracting the domain name without the subdomain from a URL using JavaScript, there are two main methods that can be used: using the window.location object or using regular expressions. Each method has its own advantages and disadvantages, and the choice between them depends on the specific use case.

Using the window.location Object

Pros:

• Easy to implement: The window.location object provides direct access to various components of the URL, including the domain name. Extracting the domain name without the subdomain can be achieved by accessing the hostname property of the window.location object.
• No need for additional libraries: Since the window.location object is built into JavaScript, no additional libraries or dependencies are required.

Cons:

• Limited support for cross-origin URLs: The window.location object only provides access to the URL of the current page. If you need to extract the domain name from a different URL, such as an external resource or an iframe, using the window.location object is not feasible.

Using Regular Expressions

Pros:

• Flexibility: Regular expressions provide a powerful and flexible way to extract specific patterns from strings. By using regular expressions, you can define custom patterns to extract the domain name without the subdomain, regardless of the URL's origin.
• Cross-origin support: Regular expressions can be used to extract the domain name from any URL, including cross-origin URLs.

Cons:

• Complexity: Regular expressions can be complex and difficult to understand, especially for beginners. Implementing a regular expression to extract the domain name without the subdomain requires knowledge of regular expression syntax and pattern matching.

Factors to Consider

When choosing the appropriate method for extracting the domain name without the subdomain, consider the following factors:

• Use case: If you only need to extract the domain name from the current page's URL, using the window.location object is a simple and straightforward option. However, if you need to extract the domain name from external resources or cross-origin URLs, regular expressions are a better choice.
• Complexity: If simplicity and ease of implementation are important, using the window.location object is recommended. On the other hand, if you require more flexibility and control over the extraction process, regular expressions are the way to go.

By considering these factors, you can choose the appropriate method for your specific use case and effectively extract the domain name without the subdomain from a URL using JavaScript.

Practical Examples

Here are some sample code snippets that demonstrate the implementation of custom JavaScript functions using both methods mentioned earlier. These examples will show you how to extract the domain name without the subdomain from a URL.

Method 1: Using the window.location Object

function extractDomainUsingLocation() {
  var url = window.location.href;
  var domain = url.split('/')[2];
  return domain;
}

// Example usage
var extractedDomain = extractDomainUsingLocation();
console.log(extractedDomain);

In this example, we define a function extractDomainUsingLocation() that uses the window.location object to get the current URL. We then split the URL using the forward slash (/) as the separator and extract the domain name from the resulting array at index 2.

Method 2: Using Regular Expressions

function extractDomainUsingRegex(url) {
  var domain = url.match(/^(?:https?:\/\/)?(?:[^@\n]+@)?(?:www\.)?([^:\/\n?]+)/im)[1];
  return domain;
}

// Example usage
var url = "https://www.example.com/path/to/page";
var extractedDomain = extractDomainUsingRegex(url);
console.log(extractedDomain);

In this example, we define a function extractDomainUsingRegex(url) that takes a URL as a parameter. We use a regular expression to match the domain name without the subdomain. The extracted domain is then returned.

These code snippets demonstrate two different methods for extracting the domain name without the subdomain from a URL in JavaScript. You can choose the method that best fits your requirements and use it in your own projects.

Conclusion

In this article, we discussed the importance of extracting the domain name without the subdomain from a URL. By extracting the domain name, we can obtain valuable information about the website, such as its owner and purpose, without being cluttered by subdomains.

We explored two methods for extracting the domain name using JavaScript. The first method involved using the window.location object, which provides access to various properties of the current URL. By accessing the hostname property, we can retrieve the domain name without the subdomain.

The second method involved using regular expressions, powerful tools for pattern matching and manipulation. By constructing a regular expression pattern that matches the domain name without the subdomain, we can extract the desired information.

Each method has its advantages and disadvantages. Using the window.location object is straightforward and requires minimal code. However, it may not be suitable for scenarios where the URL is not the current page's URL.

On the other hand, regular expressions offer more flexibility and can handle a wider range of URL formats. However, constructing and understanding regular expressions can be challenging for beginners.

When choosing the appropriate method, consider the specific requirements of your project. If you only need to extract the domain name from the current page's URL, using the window.location object is a simple and efficient solution. If you require more flexibility or need to extract the domain name from URLs that are not the current page's URL, regular expressions are a powerful option.

Implementing the appropriate method will allow you to extract the domain name without the subdomain, enabling you to analyze and utilize the information effectively.