Paulius Friedt pauliusef

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.~~

Bridging Native & React for iOS & Android

js -> native

native -> js

This API was removed in React 17

Interaction tracing with React

React recently introduced an experimental profiler API. After discussing this API with several teams at Facebook, one common piece of feedback was that the performance information would be more useful if it could be associated with the events that caused the application to render (e.g. button click, XHR response). Tracing these events (or "interactions") would enable more powerful tooling to be built around the timing information, capable of answering questions like "What caused this really slow commit?" or "How long does it typically take for this interaction to update the DOM?".

With version 16.4.3, React added experimental support for this tracing by way of a new NPM package, scheduler. However the public API for this package is not yet finalized and will likely change with upcoming minor releases, so it should be used with caution.

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.

	<!DOCTYPE html>
	<html>
	<head>
	<title>Capture Photo</title>
	<meta name="viewport" content="width=device-width,height=device-height,initial-scale=1"/>
	<script type="text/javascript" charset="utf-8" src="js/phonegap.js"></script>
	<script type="text/javascript" charset="utf-8">

	var pictureSource; // picture source
	var destinationType; // sets the format of returned value

	/* Android stock browser won't let you set font-size smaller than 8px unless you apply this. */

	:root {
	-webkit-text-size-adjust: none;
	-moz-text-size-adjust: none;
	-ms-text-size-adjust: none;
	-o-text-size-adjust: none;
	text-size-adjust: none;
	}

	// Font Smoothie copyright 2013,14,15 Torben Haase <http://pixelsvsbytes.com>
	// Source-URL <https://gist.github.com/letorbi/5177771>
	//
	// Font Smoothie is free software: you can redistribute it and/or modify it under
	// the terms of the GNU Lesser General Public License as published by the Free
	// Software Foundation, either version 3 of the License, or (at your option) any
	// later version.
	//
	// Font Smoothie is distributed in the hope that it will be useful, but WITHOUT
	// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

	(function( $ ) {
	$.fn.photoswipe = function(options){
	var galleries = [],
	_options = options;

	var init = function($this){
	galleries = [];
	$this.each(function(i, gallery){
	galleries.push({
	id: i,

	// Promise.all is good for executing many promises at once
	Promise.all([
	promise1,
	promise2
	]);

	// Promise.resolve is good for wrapping synchronous code
	Promise.resolve().then(function () {
	if (somethingIsNotRight()) {
	throw new Error("I will be rejected asynchronously!");

	#!/bin/bash
	killall Xcode
	xcrun -k
	xcodebuild -alltargets clean
	rm -rf "$(getconf DARWIN_USER_CACHE_DIR)/org.llvm.clang/ModuleCache"
	rm -rf "$(getconf DARWIN_USER_CACHE_DIR)/org.llvm.clang.$(whoami)/ModuleCache"
	rm -rf ~/Library/Developer/Xcode/DerivedData/*
	rm -rf ~/Library/Caches/com.apple.dt.Xcode/*
	open /Applications/Xcode.app