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July 5th, 2021 × #javascript#performance#asynchronous

Hasty Treat - JavaScript Event Buzzwords — Sync, Concurrent, Defer, Blocking, Workers

Discussion of JavaScript timing buzzwords like synchronous, asynchronous, blocking, callbacks, and lazy loading.

Wes Bos

Wes Bos Host

Scott Tolinski

Scott Tolinski Host

or
Show Notes Transcript

In this Hasty Treat, Scott and Wes define some JavaScript Buzzwords and talk about what they mean!

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Show Notes

03:24 - Synchronous / Async

05:23 - Multi-threaded

  • JavaScript has a single "main thread"
  • But you can have more threads with web workers

08:12 - Blocking

  • JavaScript can stop other things on the page from running
  • A script tag can block HTML from being parsed
  • Most stuff in JavaScript is non-blocking
  • Node.js write to filesystem can be blocking

10:27 - Concurrent + Parallel

13:22 - Consecutive / Waterfall

  • One after another

13:48 - Callback

17:56 - Script Tag Async + Defer

  • Doesn't block other content
  • Runs when ready - doesn't care about DOMcontentLoaded
  • Wait until the page is loaded before running
  • If the script tag is above content, don't wait for it
  • Good for things that aren't called on page load

21:54 - Lazy

  • Load it in later - maybe when it's scrolled into view, or as needed
  • Not mission-critical

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