Traditional apps are where the server delivers each HTML page separately from anchor tag clicks also known as Multi-page apps (MPS). Transitional app is a new concept put forth by Rich Harris of Svelte fame that bridges the client-server interface where the client-side of the web page can control which pages are rendered on the client-side or rendered on the server-side first.

One of the big issues of modern Single Page Apps (SPA) is the ones generated from most frameworks hide the content of the HTML from web crawlers, which gums up SEO response and category placement. Major headings and article content can't be separated out. Another characteristic of a SPA that just one big page that is counterproductive is the time it takes to load a site/page rich in image content. No matter how you slice it, JavaScript will be called upon to insert user activated updates and a lot of activity goes on behind the scenes. Performance will be impacted because the code will be bloated compared to the traditional approach. A high number of dependencites bured with the JS frameworks that support this approach can lead to difficut code to write and maintain. Complex version control and configuration libraries are in there somewhere. Accessability features are rather difficult to build in so they will probably be minimized. Not good.

So where is the optimized approach that bridges traditional simplicity and the need to satisfy extensive JS based user interface enhancements we have come to expect. One of the shining stars is Svelte with its compiled approach and flexibility to pre-render server-side and only bring to the client the code needed to fill the current DOM needs. But the page HTML is always there for the crawler to see. This is fundamentally a transitional app approach by definition. So why not just call it that and use it.