Documentation / Introduction
Introduction
Browsertime lets you automate running JavaScript in your browser primary used to collect performance metrics. What exactly does that mean?
We think of a Browsertime as having four key capabilities:
- It handles everything with the browser (Firefox/Chrome).
- It executes a batch of default and configurable JavaScript when the URL has finished loading in the browser.
- It records a video of the Browser screen used to calculate Visual Metrics.
- It lets you run Selenium scripts before and after the browser access the URL (to login a user etc).
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.
- You integrate it in your tool as a JavaScript runner that collects whatever JavaScript metrics/information you want.
To understand how Browsertime does 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 and Chrome (the implementations for the WebDriver is ChromeDriver/GeckoDriver).
- Browsertime starts FFMPEG to record a video of the browser screen
- The browser access the URL.
- When the page is finished loading (you can define yourself when that happens), Browsertime executes the default JavaScript timing metrics and collects:
- 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.
The result of the run is a JSON file with all the JavaScript metrics collected, a HAR file, a video recording of the screen and a screenshot.
Now it’s time for you to install and run Browsertime.