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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.

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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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