Pavel Moravec caryfuk

Pure ESM package

The package that linked you here is now pure ESM. It cannot be require()'d from CommonJS.

This means you have the following choices:

Use ESM yourself. (preferred)
Use import foo from 'foo' instead of const foo = require('foo') to import the package. You also need to put "type": "module" in your package.json and more. Follow the below guide.
If the package is used in an async context, you could use await import(…) from CommonJS instead of require(…).
Stay on the existing version of the package until you can move to ESM.

Reset your Xcode Install on macOS

Having troubles with Xcode or their Command Line Tools? Follow this guide to reset your Xcode instance on macOS and resolve issues such as "No Xcode or CLT version detected!"

Alternatively download Xcode directly

1) Check if Xcode is installed

xcode-select -print-path

There are lot of libs for the React Native and often it is not easy to choose the right one for the job. This is a collection of useful libs I've tried (or seen in use) over the years which worked the best for me.

Essential:

Secure storage - https://www.npmjs.com/package/rn-secure-storage
Navigation - https://www.npmjs.com/package/react-navigation
Device info - https://www.npmjs.com/package/react-native-device-info
Network info - https://www.npmjs.com/package/@react-native-community/netinfo
Push notifications - https://www.npmjs.com/package/react-native-push-notification
Permissions - https://www.npmjs.com/package/react-native-permissions

@kangax's ES6 quiz, explained

@kangax created a new interesting quiz, this time devoted to ES6 (aka ES2015). I found this quiz very interesting and quite hard (made myself 3 mistakes on first pass).

Here we go with the explanations:

Question 1:

(function(x, f = () =&gt; x) {

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

Every single JavaScript engine supports standard timers *

These accept one or more extra argument by specs

for(var i = 0; i < 2; i++) {
  setTimeout(function (i) {
    console.log(i);
  }, 0, i); // <== see this?
}

	/*<?php
	///public class PhpJava { public static void main(String[] args) { System.out.printf("/%s",
	//\u000A\u002F\u002A
	class PhpJava {
	static function main() {
	echo(//\u000A\u002A\u002F
	"Hello World!");
	}}
	//\u000A\u002F\u002A
	PhpJava::main();

	/* bling.js */
	window.$ = document.querySelector.bind(document);
	window.$$ = document.querySelectorAll.bind(document);
	Node.prototype.on = window.on = function(name, fn) { this.addEventListener(name, fn); };
	NodeList.prototype.__proto__ = Array.prototype;
	NodeList.prototype.on = function(name, fn) { this.forEach((elem) => elem.on(name, fn)); };

	/**
	* Make sure Graphicsmagick is installed on your system
	* osx: brew install graphicsmagick
	* ubuntu: apt-get install graphicsmagick
	*
	* Install these gulp plugins
	* glup, gulp-image-resize, gulp-imagemin and imagemin-pngquant
	*
	* Group images according to their output dimensions.
	* (ex: place all portfolio images into "images/portfolio"

	// HamGridSquare.js
	// Copyright 2014 Paul Brewer KI6CQ
	// License: MIT License http://opensource.org/licenses/MIT
	//
	// Javascript routines to convert from lat-lon to Maidenhead Grid Squares
	// typically used in Ham Radio Satellite operations and VHF Contests
	//
	// Inspired in part by K6WRU Walter Underwood's python answer
	// http://ham.stackexchange.com/a/244
	// to this stack overflow question: