Build, test, and debug regular expressions
Matches triple-curly-brace template tags like {{{ variable.name }}}, capturing the variable key (word characters and dots, with optional surrounding whitespace) in group 1. This is the unescaped-output syntax used by Mustache and Handlebars template engines. With global and multiline flags enabled, it extracts all variable keys throughout a template document, making it useful for template parsing, validation, or localization key extraction.