We expect this release to ship in the DevTools of Chrome 113.

Core

tracing: handle FrameCommittedInBrowser with processPseudoId (#14800)
redirects: use requestId instead of URL to find requests (#14838)
don't use failed network requests as potential initiators (#14819)
config: change error message if no artifacts are defined (#14818)
bf-cache: count failures based on affected frames (#14823)
legacy-javascript: update polyfill size graph (#14828)
prioritize-lcp-image: use request initiators for load path (#14807)
prioritize-lcp-image: better identify lcp request (#14804)
types: fix error when using moduleResolution: "node" (#14815)

Clients

lr: accept multiple channel naming conventions (#14799)

Docs

user-flows: add desktop config examples (#14806)

Tests

reenable metrics-tricky-tti on ToT (#14790)
devtools: use new primaryPageTarget function (#14839)
add roundtrip-proto lhr render test, check for undefined (#14817)
devtools: sync e2e tests (#14801)

Misc

proto: add screenEmulation to configSettings (#14809, #14826)

Full Changelog
Release article

We expect this release to ship in the DevTools of Chrome 112, and to PageSpeed Insights within 2 weeks.

New Contributors

Thanks to our new contributors 👽🐷🐰🐯🐻!

Alex N. Jose @alexnj
Alexandra White @heyawhite
Amanda @apettenati
Andrew Gutekanst @Andoryuuta
Christopher Holder @ChristopherPHolder
Dongkyun Yu (Steve) @hackurity01
Floris @FMJansen
Gabe @MrBrain295
ghost_32 @k99sharma
Littleton Riggins @TripleEquals
lowkeyAngry @lowkeyAngry
Michael McMahon @TechnologyClassroom
Shogo Hida @shogohida
Stoyan @stoyan
Yang Guo @hashseed

Notable Changes

Performance Score Changes

In the 8.0 release, we described TTI's waning role, and today we have the followup. Time to Interactive (TTI) no longer contributes to the performance score and is not displayed in the report. However, it is still accessible in the Lighthouse result JSON.

Without TTI, the weighting of Cumulative Layout Shift (CLS) has increased from 15% to 25%. See the docs for a complete breakdown of how the Performance score is calculated in 10.0, or play with the scoring calculator.

Types for the Node package

Lighthouse now includes type declarations! Our example TypeScript recipe demonstrates how to achieve proper type safety with Lighthouse.

Third-party Entity classification

Since Lighthouse 5.3, the community-driven third-party-web dataset has been used to summarize how every third-party found on a page contributes to the total JavaScript blocking time, via the third-party-summary audit. With Lighthouse 10.0, we are adding a new property to the JSON result (entities) to make further use of this dataset. Every origin encountered on a page is now classified as first-party or third-party within entities. In 10.0, this classification is used to power the existing third-party filter checkbox.

In a future version of Lighthouse, this will be used to group the table items of every audit based on the entity it originated from, and aggregate the impact of items from that specific entity.

🆕 New Audits

Back/forward cache

The Back/forward cache (bfcache for short) is a browser optimization that serves pages from fully serialized snapshots when navigating back or forwards in session history. There are over 100 different reasons why a page may not be eligible for this optimization, so to assist developers Lighthouse now attempts to trigger a bfcache response and will list anything that prevented the browser from using the bfcache. #14465

For more on bfcache, see the web.dev article.

Note: This audit initially will not be available for PageSpeed Insights.

Preventing pasting to inputs

The audit password-inputs-can-be-pasted-into is now paste-preventing-inputs. This audit's logic works just as before, but rather than just considering [type=password] inputs, it now fails if any non-readonly input element prevents the user from pasting. #14313

Lighthouse documentation is now on developer.chrome.com

Our documentation is no longer hosted on web.dev. For the most up to date audit docs, please go to developer.chrome.com/docs/lighthouse/

💥 Breaking changes

Under the hood, Lighthouse now uses the new user-flow supporting infrastructure by default, even for traditional navigation runs. You can opt out of this by: in the CLI, use --legacy-navigation; in DevTools: check “Legacy Navigation” in the settings menu. If you have a use case that necessitates this escape hatch, please file an issue. We plan to remove this legacy path in 11.0.

For Lighthouse result JSON (LHR) users

Page URLs on the Lighthouse Result

Until now, there were two URL fields to describe a Lighthouse run:

requestedUrl: the url given by the users, which Lighthouse instructs Chrome to navigate to
finalUrl: the url after any server-initiated HTTP and JS-initiated redirects

This taxonomy cannot account for more complex scenarios, such as JS-initiated redirects, usage of the History API or soft-navigations. They were also ill-defined for timespan and snapshot modes. To account for that, Lighthouse 10.0 now has these URL fields:

(changed) requestedUrl: The URL that Lighthouse initially navigated to before redirects. This is the same as it was before for navigation mode, but now it will be undefined in timespan/snapshot.
(new) mainDocumentUrl: The URL of the last document requested during a navigation. It does not account for soft navigations or history API events made after the page loads. It is only available in navigation mode, and will be undefined in timespan and snapshot modes.
(new) finalDisplayedUrl: The URL displayed in the browser combobox at the end of a Lighthouse run. It accounts for soft navigations and history API events. Available in navigation, timespan, and snapshot modes.
(deprecated) finalUrl: Same value as mainDocumentUrl.

Audit changes

password-inputs-can-be-pasted-into -> paste-preventing-inputs
preload-lcp-image -> prioritize-lcp-image
third-party-summary no longer uses a link value for item.entity, instead uses a raw text value
full-page-screenshot is no longer an audit, instead it is stored at lhr.fullPageScreenshot. To suppress collection of the full-page screenshot in the CLI, you must migrate from --skip-audits full-page-screenshot to --disable-full-page-screenshot.

For Node users

Node 14 is no longer supported, the minimum is now Node 16
In case you import paths within the lighthouse node package: lighthouse-core/ and lighthouse-cli/ folders are now simply core/ and cli/
Converted from CommonJS to ES modules. You can still use lighthouse in CommonJS by using an dynamic import: await import('lighthouse'). For access to just the lighthouse function in CommonJS, you can also use require('lighthouse/core/index.cjs')
The CSV output for Lighthouse is much more useful now. Consult the PR for an example of the new format
LHError is now LighthouseError. If you are attempting to catch an error thrown by Lighthouse, be sure to account for this!

Node API changes

The lighthouse function now has better integration with Puppeteer. Use lighthouse(url, flags, config, page) to run Lighthouse, passing an existing Puppeteer.Page handle as page.

The user flow api has moved to the top level node entrypoint and can be imported with import {startFlow} from 'lighthouse'.

New flow.startNavigation() and flow.endNavigation() functions let you define a user triggered navigation without any callback function. See the user flow docs for an example.

To change settings for a single user flow step, define the settings overrides on the toplevel flags options flow.snapshot({skipAduits: ['uses-http2']}) instead of on the settingsOverride property.

To give a flow step a custom name, use flow.snapshot({name: 'Custom name'}). Previously this was done via stepName.

For Lighthouse customization (custom config, gatherers, audits)

To work in Lighthouse 10.0, custom gatherers will need to implement the new Gatherer interface (an example). Otherwise, they will only work in legacy navigation mode and older versions of Lighthouse
Lighthouse cannot use passes to load the page multiple times in navigation mode anymore. If you need to load the page multiple times, we recommend using a user flow. See our config docs for instructions on how to convert to the new config format
The ScriptElements artifact is now Scripts, with a slightly different shape
Audit.makeOpportunityDetails and Audit.makeTableDetails now accept an options object as the third parameter. This ends up being a breaking change for just Audit.makeOpportunityDetails.