How to Create a Robust Regular Expression for Detecting URLs with or without 'http://' Prefix?

How to Construct a Comprehensive URL RegEx

RegEx patterns are a powerful tool for matching specific text formats. Identifying a URL using a RegEx pattern requires meticulous attention to ensure accurate detection.

In your case, the difficulty arises when attempting to detect URLs without the "http://" prefix. To address this, here's an enhanced RegEx pattern:

https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)

Breakdown of the Pattern:

• Protocol (Optional):

  • https? matches "http://" or "https://" (case-insensitive).

• Subdomain Prefix (Optional):

  • (www.) matches the "www." subdomain prefix.

• Domain Name:

  • [-a-zA-Z0-9@:%._ ~#=]{1,256} matches any combination of letters, numbers, and the specified special characters, with a maximum length of 256 characters.

• Top-Level Domain:

  • .[a-zA-Z0-9()]{1,6} matches the top-level domain (e.g., ".com", ".org") with a maximum length of 6 characters.

• Path and Query String (Optional):

  • b([-a-zA-Z0-9()@:%_ .~#?&//=]*) captures any additional path elements in the URL.

Alternative Regex without Required Protocol:

[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)

This version removes the protocol matching component, making it suitable for URLs like "www.google.com".

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