Krasimir Tsonev krasimir

Stuff I wish I'd known sooner about service workers

I recently had several days of extremely frustrating experiences with service workers. Here are a few things I've since learned which would have made my life much easier but which isn't particularly obvious from most of the blog posts and videos I've seen.

I'll add to this list over time – suggested additions welcome in the comments or via twitter.com/rich_harris.

Use Canary for development instead of Chrome stable

~~Chrome 51 has some pretty wild behaviour related to console.log in service workers. Canary doesn't, and it has a load of really good service worker related stuff in devtools.~~

Array Iteration

https://gist.github.com/ljharb/58faf1cfcb4e6808f74aae4ef7944cff

While attempting to explain JavaScript's reduce method on arrays, conceptually, I came up with the following - hopefully it's helpful; happy to tweak it if anyone has suggestions.

Intro

JavaScript Arrays have lots of built in methods on their prototype. Some of them mutate - ie, they change the underlying array in-place. Luckily, most of them do not - they instead return an entirely distinct array. Since arrays are conceptually a contiguous list of items, it helps code clarity and maintainability a lot to be able to operate on them in a "functional" way. (I'll also insist on referring to an array as a "list" - although in some languages, List is a native data type, in JS and this post, I'm referring to the concept. Everywhere I use the word "list" you can assume I'm talking about a JS Array) This means, to perform a single operation on the list as a whole ("atomically"), and to return a new list - thus making it mu

Rxjs

const next = (message)=> console.log("First observer message: " + message);
const error = (error) => console.log("Second observer error: " + error);
const complete = () => console.log("complete");

const next1 = (message)=> console.log("First observer message 1: " + message);
const error1 = (error) => console.log("Second observer error 1: " + error);
const complete1 = () => console.log("complete 1");

	"use strict";

	[foo,bar] = TNG(foo,bar);
	// NOTE: intentionally not TNG(..) wrapping useBaz(), so that it's
	// basically like a "custom hook" that can be called only from other
	// TNG-wrapped functions

	function foo(origX,origY) {
	var [x,setX] = useState(origX);
	var [y,setY] = useState(origY);