Ioan Lucut ioanlucut

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.

Redux containers: `mapDispatchToProps`

This document details some tips and tricks for creating redux containers. Specifically, this document is looking at the mapDispatchToProps argument of the connect function from [react-redux][react-redux]. There are many ways to write the same thing in redux. This gist covers the various forms that mapDispatchToProps can take.

Regular Event Loop

This shows the execution order given JavaScript's Call Stack, Event Loop, and any asynchronous APIs provided in the JS execution environment (in this example; Web APIs in a Browser environment)

Given the code

$ npm install --save babel-cli babel-preset-es2015
$ npm install --save-dev jasmine

.babelrc:

{
 "presets": ["es2015"]

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

Hi Nicholas,

I saw you tweet about JSX yesterday. It seemed like the discussion devolved pretty quickly but I wanted to share our experience over the last year. I understand your concerns. I've made similar remarks about JSX. When we started using it Planning Center, I led the charge to write React without it. I don't imagine I'd have much to say that you haven't considered but, if it's helpful, here's a pattern that changed my opinion:

The idea that "React is the V in MVC" is disingenuous. It's a good pitch but, for many of us, it feels like in invitation to repeat our history of coupled views. In practice, React is the V and the C. Dan Abramov describes the division as Smart and Dumb Components. At our office, we call them stateless and container components (view-controllers if we're Flux). The idea is pretty simple: components can't

	#!/bin/bash

	#
	# Inspects branch name and checks if it contains a Jira ticket number (i.e. ABC-123).
	# If yes, commit message will be automatically prepended with [ABC-123].
	#
	# Useful for looking through git history and relating a commit or group of commits
	# back to a user story.
	#

	/*
	Let us re-create `Promise.all`

	`Promise.all` method returns a promise that resolves when all of the promises in the iterable argument have resolved,
	or rejects with the reason of the first passed promise that rejects.

	Read more about `Promise.all` on MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all

	A basic example would be something like this:

	// This example shows the difference
	// between classNames, classNames/bind and classnames-loader


	// submit-button.css
	/*
	:local .className {
	color: green;
	background: red;
	}

	#!/bin/bash

	firstLine=`head -2 $1 \| tail -1`
	if [[ $firstLine == \#* ]]; then # Testing that the file starts with a comment, not yet a real commit ;)
	echo '<type>(<component>): <subject>' > .prepare-commit-msg-temp
	echo '' >> .prepare-commit-msg-temp
	echo '<body>' >> .prepare-commit-msg-temp
	echo '' >> .prepare-commit-msg-temp
	echo '# types: feat, fix, docs, style, refactor, test, chore(mantean)' >> .prepare-commit-msg-temp