Probably referring to using pushState (part of the History API) to update the URL to a bookmarkable fragment URL, or even to a regular path leading to a created document.

https://developer.mozilla.org/en-US/docs/Web/API/History/pus...

> The new history entry's URL. Note that the browser won't attempt to load this URL after a call to pushState(), but it may attempt to load the URL later, for instance, after the user restarts the browser.