lab-assistant
lab-assistant is a Puppeteer-based tool that does the grunt work of taking
measurements and figuring out how much of a performance change there is between
two different versions of your site.
This is a useful tool to run every time you're working on a loading performance improvement. It will help you gauge whether the improvement is real and not just placebo, and it'll give you a number to attach to your PR description, blog post, or annual employee self-assessment survey.
Impress your peers with actual numbers!
Usage
The easiest way to use lab-assistant is with a tool like
npx:
npx lab-assistant http://v1.mysite.tld http://v2.mysite.tld
Here's the current full set of options (which you can get with --help):
lab-assistant.js <url> [url2]
Positionals:
url URL to fetch content from.
If `url2` is not specified, this is used for both the new and old
versions, with the application pausing in between to allow for the
version swap.
url2 Second URL to fetch content from.
If specified, this refers to the new version, while `url` refers to
the old version.
Options:
--help Show help [boolean]
--verbose, -v Output more details. [boolean] [default: false]
--headless Whether to use a headless browser.
[boolean] [default: true]
--repeat, -r The number of measurements to take for each version.
[number] [default: 10]
--throwaway, -t The number of throwaway visits to perform before any
actual measurements.
Keeping it at 1 or increasing the value can help with
stability. [number] [default: 1]
--cpu_slowdown, -c The CPU slowdown throttling to apply (may help achieve
more stable results in CPU-heavy pages). [number]
--metric, -m The metric to consider.
Metrics:
- ttfb: Time to First Byte
- fp: First Paint
- fcp: First Contentful Paint
- dcl: Time to DOMContentLoad event end
- load: Time to Load event end
[string] [choices: "ttfb", "fp", "fcp", "dcl", "load"] [default: "load"]
License
lab-assistant is licensed under GNU General Public License v2 (or later).