Browser agent release notesRSS

This release is in public preview. We're slowly rolling out these features to different browser agents based on the browser's instrumentation method. Here's the release timeline:

• Internal NR Platform release date: 10/07/2022
• Production APM-injected release date: 10/7/2022
• Production Standalone release date: Estimated around 12/13/2022

New Features

Capture unhandled Promise rejections

The Agent now observes and captures unhandled Promise rejections as JavaScript Error objects.

Removed 3rd Party Cookies

The browser agent no longer uses 3rd party cookies to maintain and track session information. 1st party implementation using window.sessionStorage is now used, which is automatically cleared when a page session ends. This is still managed using the privacy settings form in your browser application settings.

LCP is no longer reported on initially-hidden pages

LCP metrics are no longer reported on pages whose state is hidden at load time, such as tabs refreshing in the background of a focused tab.

Async Module Loading

Individual features of the browser agent can now be dynamically loaded, enabled, or disabled at runtime.

Removal of script tag injection

The agent no longer inserts other features into the page via a script tag insertion. It now uses network requests to instantiate other code modules.

Updated test process

In an effort to better support the majority of our traffic, the test suite required to merge PRs has been updated to run against the latest 10 major versions of Chrome, Firefox, Edge, Android, and the latest 5 major versions of Safari and iOS. As part of this process, outdated code and polyfill libraries aimed at supporting deprecated browsers are no longer included in production builds by default.

Bug Fixes

Fixed issue with BrowserInteraction nodes generating circular references

BrowserInteractions no longer generate circular trees when they are self referential.

Remove non-ASCII characters from builds

Certain dependencies were appending non-ASCII characters to build files. These characters were affecting older Python agent implementations downstream that worked to parse and encode the agent snippet. The build files are now checked and cleaned of non-ASCII characters before shipping.

• Internal NR Platform release date: 04/19/2022
• Production APM-injected release date: 04/20/2022
• Production Standalone release date: 04/27/2022

New Features

Introduced obfuscation mechanism to payloads

Added internal mechanism for applying regex and replacement rules to all strings in payloads to obfuscate before sending to ingest.

Automatically obfuscate file:// protocol

A change has been implemented in our handling of applications hosted locally on a file:// protocol. For security reasons, we can not send payloads that contain file information, so our previous implementation revolved around completely shutting the agent down when file:// protocols were detected. This change automatically obfuscates all file:// paths from our payloads before sending to ingest.

Bug Fixes

Fixed issue with trace ID random hex character length

The final character in trace ID hex generation was returning as undefined, which translated to always be 0 (undefined & 15 === 0). This change fixes this final character and ensures it is valid.

Improvements

• Internal NR Platform release date: 01/24/2021
• Production APM-injected release date: TBD
• Production Standalone release date: TBD

Collect supportability metrics for frontend frameworks

Added frontend framework detection metrics to help guide future priorities for browser agent features. The following frontend frameworks will now be detected and analyzed:

• React
• Angular
• AngularJS
• Backbone
• Ember
• Vue
• Meteor
• Zepto
• Jquery

Improvements

Added NetworkInformation attributes to LCP & FI

The Largest Contentful Paint (largestContentfulPaint) and First Interaction (firstInteraction) PageViewTiming events will now include attributes from the NetworkInformation API (on compatible browsers) observed on the page. This includes network type (networkType), round trip time (rtt) and downlink (downlink).

Added element identification attributes to LargestContentfulPaint

LargestContentfulPaint PageViewTiming events will now include the elementTagName attribute which represents the triggering element's tag name. If the triggering element is an image, the event will also include the elementUrl representing the image URL if present.

Included page view timing data in session trace payload

If observed, the agent will now include PageViewTiming events in the session trace waterfall payload. These events will be available in an upcoming update to the session traces UI.

Added session trace IDs to harvests

If a session trace is active on a page, a session trace ID associated with that trace will now be appended to all subsequent events generated on the page for the linking of session-related datasets downstream. This ID will be appended to any payload that sent after a session trace has been started. PageView events are generated before session traces begin and will not contain this ID and in most cases Initial Page Load BrowserInteraction events complete before a session trace begins and are not guaranteed to contain this ID.

Bug fixes

Exclude Data URL requests from Ajax events and metrics

Previously, XMLHttpRequest and Fetch calls made with Data URLs could prevent the agent from harvesting data.

Improvements

Updated LCP tracking

Largest Contentful Paint will now stop being tracked when page visibility changes to hidden. This aligns with the web-vitals library.

Added passive flag to addEventListener calls

Using the addEventEventListener without the passive flag for the touchstart event is flagged in Lighthouse. The passive flag is now applied to all addEventListener calls in the agent.

Update to Cumulative Layout Shift calculation

The CLS calculation has been updated to use session windows in order to align with Google Chrome tooling (Lighthouse, PageSpeed Insights, CrUX). For more information, see the official blog post on web.dev.

Bug Fixes

Fixed issue with Array.isArray() call

Array.isArray() call is not supported on old browsers and can cause a runtime error. This call has been replaced with an alternative that works on older browsers.

Fixed issue with null function argument in the addEventListener API

When a null value was passed in to the addEventListener API, the agent would report an internal error. This edge case is now being handled.

Fixed issue with Ajax deny list

There was an edge case where certain ajax calls could have been excluded when they should not have been. This is now handled correctly.

Miscellaneous

Added support for collecting internal/supportability metrics

The agent can now send metrics that capture information about how the agent itself is working internally.

Added agent supportability metrics for tracking API usage

Added agent supportability metrics for tracking excluded Ajax events

Improvements

AjaxRequest events for all XHR/fetch requests

Previously, XHR/fetch requests were captured as AjaxRequest events only when they were part of a route change. With this change, all requests will be captured as events. This feature can be further configured by specifying which requests should not be collected.

Span events are for all XHR/fetch requests

Previously, Span events were generated only for XHR/fetch requests that were part of a route change. With this change, all requests will be captured as Spans.

Update to Cumulative Layout Shift calculation

The CLS calculation has been updated to use session windows in order to align with Google Chrome tooling (Lighthouse, PageSpeed Insights, CrUX). For more information, see the official blog post on web.dev.

Bug Fixes

Prevent duplicate session trace nodes

The agent no longer calls the clearResourceTimings API, which had the potential to affect other scripts from accessing all resources. Instead, it now uses the PerformanceObserver API to collect information about resources.

Improvements

PageHide PageViewTiming events are now accounted for during page unload events

PageHide PageViewTiming events are used to query CLS values. In cases where the page was never hidden, inconsistencies would arise because the PageViewTiming event with that type would not be collected. Now when pageUnload fires, if a pageHide PageViewTiming has not already been set, it will set it to the time of unload.

Perfect Cumulative Layout Scores (CLS) are now recorded as 0

Perfect CLS scores were being ignored, because a score was only recorded when content shifted. This change reports perfect scores as 0, fixing inconsistent CLS queries.

Record fetch calls as metrics

Fetch calls are currently only recorded as AjaxRequest events with SPA browser interactions. This change records fetch calls as AJAX metrics, which will make them visible in the AJAX UI charts.

Improvements

Doubled the limit of PageAction events per harvest

Up to 120 PageAction events can be harvested every 30 seconds.

Removed call to /ping endpoint

Removed a legacy behavior used to ensure network connection was kept alive in IE 7/8/9.

Bug Fixes

Prevent duplicate session trace nodes

The final Session Trace node in a harvest, captured using the Resource Timing API, is no longer duplicated in the subsequent harvest.

This issue lead to 1 duplicate node in a Session Trace, every 10 seconds, over the duration of the trace.

Memory overhead when agent script

Fixed a memory leak in the agent when the network request to load the second part of the agent is blocked.

Update to file protocol restriction

Fixed an error thrown in the console when the agent is loaded using the file:// protocol caused by features in the agent trying to run when others had been aborted.

setTimeouts without callback functions

Fixed an issue where route change Browser Interactions would wait forever if a setTimeout was called without a callback function (passing code in as a string in the first argument) as the first argument.

Cypress.io

Fixed a conflict between the Browser agent and the Cypress.io test framework when instrumenting XMLHttpRequest.

Improvements

Retry harvest network requests

The agent retries harvest XHR requests when it receives 408, 429, 500 or 503 response codes. Additionally, includes a security update to address NR21-01.

File protocol disallowed

The agent will not report any data when it is on a page opened from a local file.