`ts-req-history`

If this directive is supplied on the origin element, TwinSpark will push response URL as a new page URL.

URLs are a fundament of the Web. Changing URLs in line with activity makes your app reloadable, browseable with backward/forward button and overall a good citizen of the Web.

Browser’s API for changing history (history.pushState) gives you ability to store “current” HTML, so you could restore it on popstate event. Of course, Firefox limits this storage to 640Kb, so it breaks for long pages.

More than that, on real page change, browser does not do anything special. And if you click “back” there, it shows you HTML from previous real page load. So if you’re on a product listing page with endless scroll, all that products you just saw are gone.

Because of that TwinSpark is using IndexedDB to store current page HTML on every pushState and on beforeunload events. This storage is limited to 20 pages (configurable). There is a post with details called History Snapshotting in TwinSpark.

Notes

ts-req-history="replace" will replace current page URL rather than push a new history item.
ts-history header can specify new URL if you want it distinct from the request URL.
Redirecting request will force TwinSpark to make a full page change, with document.body becoming new origin element.