Is Your JavaScript String a Valid URL?

How to Determine if a JavaScript String Represents a URL

In JavaScript, you may encounter scenarios where you need to determine if a given string is a valid URL. While regular expressions offer a versatile approach, certain URL formats, such as "stackoverflow," lack standard elements like ".com," "www," or "http."

To handle such cases, a more robust method is utilizing the URL constructor.

Solution:

To check if a string represents a valid HTTP URL, you can employ the following function:

function isValidHttpUrl(string) {
  try {
    const url = new URL(string);
    return url.protocol === "http:" || url.protocol === "https:";
  } catch (_) {
    return false;
  }
}

This function will instantiate a new URL object with the provided string. If the string adheres to the proper URL format, it will succeed without throwing an error.

Note:

It's important to consider that not all URLs must start with "http" or "https." According to RFC 3886, URLs can commence with various schemes. Here are some examples:

• "www.example.com" is not a valid URL due to the absence of a scheme.
• "javascript:void(0)" is a valid URL but not an HTTP URL.
• "http://.." is a valid URL with an unconventional host.
• "https://example..com" is also a valid URL, with the double period indicative of a non-standard host.

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