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!
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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
- 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
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