sebmarkbage

The Rules of React

All libraries have subtle rules that you have to follow for them to work well. Often these are implied and undocumented rules that you have to learn as you go. This is an attempt to document the rules of React renders. Ideally a type system could enforce it.

What Functions Are "Pure"?

A number of methods in React are assumed to be "pure".

On classes that's the constructor, getDerivedStateFromProps, shouldComponentUpdate and render.

bvaughn

React recently introduced an experimental profiler API. This page gives instructions on how to use this API in a production release of your app.

Table of Contents

• Profiling in production
  • Create React App
  • Webpack 4

Profiling in production

React DOM automatically supports profiling in development mode for v16.5+, but since profiling adds some small additional overhead it is opt-in for production mode. This gist explains how to opt-in.

mohanpedala

Table of Contents

• set -e, -u, -x, -o pipefail
• set -e
• set -x
• set -u
• set -o pipefail
• Setting IFS
• Original Reference

set -e, -u, -x, -o pipefail

gaearon

If you use server rendering, keep in mind that neither useLayoutEffect nor useEffect can run until the JavaScript is downloaded.

You might see a warning if you try to useLayoutEffect on the server. Here's two common ways to fix it.

Option 1: Convert to useEffect

If this effect isn't important for first render (i.e. if the UI still looks valid before it runs), then useEffect instead.

function MyComponent() {

kangax

/*

  A collection of tests where Flow and TypeScript might have different behavior
  Some tests are borrowed from https://github.com/vkurchatkin/typescript-vs-flow
  Some tests now have the same behavior as the new versions of Flow/TS have fixed the bugs and improved type safety

*/


/* 1. Accessing unknown properties on objects */

robrichard

Using @defer under an array field will return multiple patches. Patches are unique combinations of label and path

{
  items {
    id
    ...frag @defer(label: "my-label")
  }
}

gaearon

class Spiderman {
  lookOut() {
    alert('My Spider-Sense is tingling.');
  }
}

let miles = new Spiderman();
miles.lookOut();

davidpark-blade

git archive --format=zip HEAD `git diff HEAD~1..HEAD --name-only --diff-filter=d  | grep -E 'config/locales/.+\.yml|frontend/translations/.+\.js'` > files-changed-to-translate.zip
// change 1 to number of commits in pr