Hashbang Routing
Hashbang routing is a client-side routing technique used in single-page applications (SPAs) where URLs contain a hash (#) followed by an exclamation mark (!), typically in the format #!path. It was developed to enable AJAX-based applications to be crawlable by search engines by providing server-side fallbacks for hash fragments. This approach allows SPAs to maintain state and navigation without full page reloads while improving SEO compatibility.
Developers should learn hashbang routing when building SPAs that require search engine optimization, as it was a historical solution to make dynamic content indexable before modern search engines supported JavaScript rendering. It is particularly useful in legacy applications or when targeting older browsers that lack support for HTML5 History API, though it has largely been superseded by pushState-based routing in modern web development.