Browsertime - Your browser, your page, your scripts!
Access the Web Performance Timeline, from your browser, in your terminal!
We think of a Browsertime as having four key capabilities:
- It handles everything with the browser (Firefox/Chrome/Edge/Safari).
- It records a video of the Browser screen used to calculate Visual Metrics.
- It lets you run your scripting file to create and measure your users journey.
What is Browsertime good for?
It is usually used for two different things:
- You run it as a standalone tool to collect performance timing metrics of your web site.
To understand how Browsertime do these things, let's talk about how it works. Here's an example of what happens when you give Browsertime a URL to test:
- You give your configuration to Browsertime.
- Browsertime uses the WebDriver (through Selenium) to start Firefox/Chrome/Safari/Edge.
- Browsertime starts FFMPEG to record a video of the browser screen
- The browser access the URL.
- It also collects a HAR file that shows all requests/responses on the page.
- FFMpeg is stopped and the video is analysed. Browsertime collect Visual Metrics like Speed Index.
A simple example
Use our Docker image (with Chrome, Firefox, XVFB and the dependencies needed to record a video):
$ docker run --rm -v "$(pwd)":/browsertime sitespeedio/browsertime https://www.sitespeed.io/
Or using node:
$ npm install browsertime -g $ browsertime https://www.sitespeed.io/
Load https://www.sitespeed.io/ in Chrome three times. Results are stored in a JSON file (browsertime.json) with the timing data, and a HAR file (browsertime.har) in browsertime-results/www.sitespeed.io/$date/
I want more examples
Checkout the examples.
Browsertime supports Firefox, Chrome, and Edge (Chromium version) on desktop. There are also iimited support for Safari on desktop. On Android we support Chrome and Firefox (from 8.0) and Safari on iOS.
How does it work
Speed Index and video
The default video will include a timer and showing when the metrics happens, but you can turn that off using
Test using Docker
You can build and test changes using Docker locally.
$ docker build -t sitespeedio/browsertime . $ docker run --rm -v "$(pwd)":/browsertime sitespeedio/browsertime -n 1 https://www.sitespeed.io/
You can throttle the connection to make the connectivity slower to make it easier to catch regressions. The best way to do that is to setup a network bridge in Docker or use our connectivity engine Throttle. Read more about how to do that in the documentation.
Navigate in a script
If you need a more complicated test scenario, you can define your own (Selenium)test script that will do the testing. Use your own test script when you want to test your page as a logged in user, the login page or if you want to add things to your cart.
We have a full section in the documentation about scripting.
Test on your mobile device
Browsertime supports Chrome and Firefox on Android: Collecting SpeedIndex, HAR and video!
$ browsertime --chrome.android.package com.android.chrome https://www.sitespeed.io --video --visualMetrics
If you are on Linux (we have tested Ubuntu 18) you can use our Docker container to drive your Android phone. A couple of things to remember:
- You need to run in privileged mode --privileged if you share the full usb bus
- You need to share the USB ports -v /dev/bus/usb:/dev/bus/usb or share a specific port with --device=/dev/bus/usb/001/017 (use lsusb to find the right mapping)
- Add -e START_ADB_SERVER=true to start the adb server
If you use Docker you will automatically get support for video and SpeedIndex. You can get that without Docker but then need to install VisualMetrics dependencies yourself.
$ docker run --privileged -v /dev/bus/usb:/dev/bus/usb -e START_ADB_SERVER=true --rm -v "$(pwd)":/browsertime-results sitespeedio/browsertime -n 1 --android --visualMetrics --video https://en.m.wikipedia.org/wiki/Barack_Obama
$ bin/browsertime.js --help and you can see the configuration options.
Our Docker container now included WebPageReplay.
WebPageReplay will let you replay your page locally (getting rid of server latency etc) and makes it easier to find front end regressions.
It works like this:
- The start script starts WebPageReplay in record mode
- Then starts Browsertime accessing the URL you choose one time (so it is recorded)
- WebPageReplay is closed down
- WebPageReplay in replay mode is started
- Browsertime access the URL so many times you choose
- WebPageReplay in replay mode is closed down
You can change latency by setting a Docker environment variable. Use REPLAY to turn on the reply functionality.
Default browser is Chrome:
docker run --cap-add=NET_ADMIN --rm -v "$(pwd)":/browsertime -e REPLAY=true -e LATENCY=100 sitespeedio/browsertime:9.2.1 https://en.wikipedia.org/wiki/Barack_Obama
docker run --cap-add=NET_ADMIN --rm -v "$(pwd)":/browsertime -e REPLAY=true -e LATENCY=100 sitespeedio/browsertime:9.2.1 -b firefox -n 11 https://en.wikipedia.org/wiki/Barack_Obama
And Chrome on your Android phone. This will only work on Linux because you need to be able to mount the usb port in Docker:
docker run --privileged -v /dev/bus/usb:/dev/bus/usb -e START_ADB_SERVER=true --cap-add=NET_ADMIN --rm -v “$(pwd)“:/browsertime -e REPLAY=true -e LATENCY=100 sitespeedio/browsertime https://en.m.wikipedia.org/wiki/Barack_Obama --android --chrome.args ignore-certificate-errors-spki-list=PhrPvGIaAMmd29hj8BCZOq096yj7uMpRNHpn5PDxI6I= -n 11 --chrome.args user-data-dir=/data/tmp/chrome
Send metrics to Graphite
The easiest way to send metrics is to install jq and use it to pick the values you wanna track.
Here's an example on how you can pickup the median SpeedIndex from Browsertime and send it to your Graphite instance.
echo "browsertime.your.key.SpeedIndex.median" $(cat /tmp/browsertime/browsertime.json | jq ..statistics.visualMetrics.SpeedIndex.median) "`date +%s`" | nc -q0 my.graphite.com 2003