New Features
EXPERIMENTAL - Unblock instrumented pages from the back/forward cache (w/ feature flag)
An instrumented page's back-forward cache eligibility was hampered by the agent's unload listener, which will be removed when a feature flag is on. With the allow_bfcache enabled in the init config, the agent's definition of (the end of) an user's session is more refined, and it will no longer be blocking the browser from utilizing its respective b/f cache.
Internal
Reduce size of builds for modern browser targets
The agent is now compatible with only modern web syntax (ES6+); this reduces loader size for these browsers by 20% or more. We target and test support for just the last ten versions of Chrome, Edge, Safari, and Firefox -- see browser agent EOL policy for more details.
Bug Fixes
Prevent feature from collecting and harvesting future data if account entitlements are invalid
The agent will now attempt to shut down an initialized feature if account entitlements are invalid. Accounts that lack entitlements to use certain endpoints will see many 403 errors in the console without this behavior. This behavior requires the Page View Event feature to be enabled.
Do not collect XHR events for data URLs
AJAX events for data URLs have not historically been collected due to errors in the agent when handling URLs without hostnames. Going forward, XHR calls to data URLs will not cause agent errors and will continue to be excluded from collection.
Fix nrWrapper exclusion in error stack traces
Restoring previous functionality whereby the nrWrapper agent method should be excluded from JavaScript error stack traces.
Fix errors with global self redefinition
Fixing an issue where external code redefining the self global variable causes the agent async loading to fail and the agent to crash.
Fix check for sessionStorage object
Ensure the agent does not crash when sessionStorage is not available or when the quota has been exceeded or set to 0.