How do I check if a value is a valid URL in JavaScript?
Benjamin C
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To check if a value is a valid URL in JavaScript, you can use regular expressions (regex) to match the URL pattern. Here's a step-by-step guide on how to do it: 1. Define the regular expression pattern: - Start by defining the regex pattern that matches the URL format. There are various regex patterns available, but for simplicity, we'll use a basic pattern that covers most standard URLs.


   const urlPattern = /^(?:https?|ftp):\/\/[^\s/$.?#].[^\s]*$/i;

This pattern checks if the URL starts with eitherhttp://,https://, orftp:// and is followed by a valid domain name. 2. Use the regular expression to test the value: - Apply the regex pattern to the value you want to validate using thetest() method.


   function isValidURL(value) {
     return urlPattern.test(value);

   console.log(isValidURL("")); // Output: true
   console.log(isValidURL("")); // Output: false
   console.log(isValidURL("invalid-url")); // Output: false

In this example, theisValidURL() function uses thetest() method on the regex pattern to check if the value matches the URL format. It returnstrue if the value is a valid URL, andfalse otherwise. 3. Customizing the URL pattern: - The provided regex pattern is a basic one and may not cover all possible URL formats. You can customize the pattern according to your specific requirements. - There are more comprehensive regex patterns available that cover various URL formats, including schemes, domains, paths, query strings, and fragments. You can search for such patterns or modify the existing pattern based on your needs.


   const urlPattern = /^(?:(?:https?|ftp):\/\/)?(?:www\.)?[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}(?:\/\S*)?$/;

This modified pattern allows optional scheme (http://,https://, orftp://) andwww subdomain, followed by a valid domain name and an optional path. By following these steps, you can check if a value is a valid URL in JavaScript. Keep in mind that the provided regex patterns are basic and may not cover all edge cases. If you have specific requirements or need to handle more complex URL formats, consider using more comprehensive regex patterns or external libraries that offer URL validation functionality.