Regex Tester & Validator

This regex extracts the URL from the `src` attribute of HTML elements, such as `<iframe>` tags, capturing it in a named group called `url`. It accommodates both single and double quotes using a backreference to ensure matching pairs. Additionally, it supports both absolute (`http://` or `https://`) and protocol-relative (`//`) URLs. This pattern is highly useful for parsing HTML content to locate and extract embedded resources.