Soft navigation

A soft navigation is a client-side routing navigation used by Single Page Applications (SPAs) to load new content.

Typically, clicking a link on a webpage loads a completely new page (a "hard navigation"), which can result in considerable unnecessary work, and loss of state when navigating between similar pages on a site.

Modern JavaScript frameworks use client-side routing to intercept link clicks, update the content on the current page (perhaps after making Fetch calls), and then update the URL in the address bar while pushing a history state entry for the resulting navigation.

The net effect appears to be a navigation to the user (but hopefully faster than a hard navigation), which the browser will see as the same page.

The PerformanceSoftNavigation and InteractionContentfulPaint APIs allow measurement of soft navigations outside of a framework for performance metrics.