Lighthouse is an
open-source, automated tool for
improving the quality of your web apps. You can install it as a
[Chrome Extension][crx] or run it as a Node command line tool. When you
give Lighthouse a URL, it runs a barrage of tests against the page and then
generates a report explaining how well the page did and indicating areas for
Today, we’re happy to announce the
of Lighthouse, a huge release, with over 128 PRs. Lighthouse 1.5 includes
a bunch of big new features, audits, and the usual bug fixes. You can install
it from npm (
npm i -g lighthouse) or
download the extension
from the Chrome Web Store.
The CSS Usage Audit reports the number of unused style rules in your page
and the cost/time savings of removing them:
The Optimized Images Audit reports images that are unoptimized and the
cost/time savings of optimizing them:
The Responsive Images Audit reports images that are too big and the
potential cost/time savings of sizing them correctly for the given device:
The Deprecations and Interventions Audit lists console warnings from Chrome
if your page is using deprecated APIs or features that have
As you’ve seen, we’ve focused on making the report less visually cluttered by
adding tabular data, hiding extraneous help text, and adding new features to
make it easier to navigate the data.
It’s easy to forget what throttling and emulation settings were used for a
particular Lighthouse run. Lighthouse reports now include the
runtime emulation settings that were used to create the report; a
long time feature request:
Lighthouse metrics like “First meaningful paint”, “Time to Interactive”, etc are
mocked out as User Timing measures and injected back into the trace data saved
If you use the
--save-assets flag, you can now drop the trace into DevTools or
open it in the DevTools Timeline Viewer.
You’ll be able to see your key metrics in context with the full trace of the
In HTML reports, you’ll notice a new button with options for exporting the
report in different formats. One of those options is “Open in Viewer”. Clicking
this button will send the report to the online
Viewer, where you can
further share the report with GitHub users.
Behind the scenes, Viewer gets your permission via OAuth to create a GitHub
secret gist and
saves the report there. Since it’s done as your Gist, you maintain full control
over the sharing of the report and you can delete it at any time. You can revoke
the Viewer’s permission to create gists under your
The first version of the
project has landed in 1.5.0. This lets you experiment with your page load performance,
interactively testing the effects of blocking or delaying assets in your critical
path during development.
When Lighthouse is run with the
--interactive flag, a special report is
generated that allows interactive selection of costly page resources. The
experiment server then reruns Lighthouse on that page with those resources
about the Performance Experiment in Lighthouse.
Last but not least, we’ve modernized the documentation at
and added new audit references.
That’s it for now!
For all the details on the latest in Lighthouse, see the
full release notes
over on Github. As always,
hit us up
to report bugs, file
feature requests, or brainstorm
on what you’d like to see next.
Source: Lighthouse January 2017 update