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

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

Get a 30 day free trial of Freshbooks at freshbooks.com/syntax and put SYNTAX in the “How did you hear about us?” section.

If you want to know what’s happening with your code, track errors and monitor performance with Sentry. Sentry’s Application Monitoring platform helps developers see performance issues, fix errors faster, and optimize their code health. Cut your time on error resolution from hours to minutes. It works with any language and integrates with dozens of other services. Syntax listeners new to Sentry can get two months for free by visiting Sentry.io and using the coupon code TASTYTREAT during sign up.

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

• JavaScript start/stop are concurrent
• The API runs on a different thread
• Doesn’t REALLY matter
• https://joearms.github.io/published/2013-04-05-concurrent-and-parallel-programming.html

13:22 - Consecutive / Waterfall

• One after another

13:48 - Callback

• A function to run when this thing happens or is done
• Click event callback
• Websocket on data callback
  • Like a tweet stream
• Data fetch callback
  • Almost entirely replaced with async + await
• http://callbackhell.com/
• https://caolan.github.io/async/v3/

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

• Scott’s Instagram
• LevelUpTutorials Instagram
• Wes’ Instagram
• Wes’ Twitter
• Wes’ Facebook
• Scott’s Twitter
• Make sure to include @SyntaxFM in your tweets