Dev Tools Tabs Explained — Plus Tips & Tricks


In this episode of Syntax, Scott and Wes talk about dev tools tabs, what each tab does and how you can use them.

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Show Notes

3:50 - Network

  • See all requests, filter by type or name
  • Used to understand all requests coming or going
  • Turn off caching
  • View timing
  • See the true GZIP size
  • Slow down network speed
  • See time for page load
  • Copy as fetch or CURL
  • View request, response, and headers
  • See CORS issues
  • See which requests have happened
  • See if an asset is cached (both in dev tools, also Cloudflare)
  • See blocked requests because of extensions
  • Tip: You can see the network info from the console in Firefox

22:03 - Memory

  • See what is taking up memory
    • Strings
    • DOM nodes
    • Objects
    • Actual .js

26:44 - Performance

  • Click record and use the site
  • Flame chart useful for finding slow functions and debugging janky animations
  • Get FPS in coordination with flame chart
  • Save performance recording data to be able to share for debugging
  • You can also upload saved data to debug without using the site

30:48 - Console

  • Interfaces with the JS runtime
  • Shows errors, warnings, and logs
  • Tip: Negate noisy warnings/errors that clutter your console with -
  • Tip: Use $0 to select current element
    • $1 for second last
    • $r for current React element
  • Tip: Use $$ to shortcut Query SelectorAll and Array.from
  • Tip: Use $ to shortcut Query Selector

40:28 - Storage / Application

  • Working with LocalStorage, Cookies, Index DB, and Session Storage

44:56 - Audit / Lighthouse (Chrome and Firefox)

  • Run lighthouse to check for performance, accessibility, and UI stuff
  • Not the silver bullet audit that many people think it is
    • Colors are sometimes like “Really?!”
  • Can be helpful regardless

50:28 - DOM Tab

  • Firefox only
  • Shows everything that is in the scope of the browser
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