Jan Grzegorowski

tools

Devstack set up on the Virtualbox VM

This tutorial will show you how to set up and deploy a simple OpenStack based local cloud. Thanks to the automation you will be able to…

tools

How to test cloud-init locally with Vagrant

How to test a cloud-init file locally? The most straight forward choice seems to be VirtualBox and Vagrant. I will show you how to set up…

react

React Typescript library with Rollup and Jest - Storybook setup

In this part of React Typescript library setup tutorial I will describe how you can add Storybook base documentation for your components. If…

react

React Typescript library with Rollup and Jest - tests setup

If you are starting from this page I would suggest you to go back to the part 1 of this tutorial where initial Rollup and Typescript setup…

mac

How to remap single Mac keyboard key

How to remap one Mac OS X keyboard key to the other without using any external tools? Is it even possible to do without being a mac…

react

React Typescript library with Rollup and Jest - adding React

If you are starting from this page I would suggest you to go back to the part 1 of this tutorial where initial Rollup and Typescript setup…

react

React Typescript library with Rollup and Jest - initialization

Here is a tutorial which will show you how to create your own NPM package with React components written in Typescript. You can check https…

javascript

What are NPM dist tags and how to use them

While developing or using NPM package registry you may come across command or multiple dist tags available for one package e.g. next tag…

javascript

How to mock global window variables with Jest

While generally everything is extremely easy using Jest, mocking global variables is one thing which is left up to developer. You can…

javascript

Custom Jest transformer CSV example

Sometimes you may need a custom Jest transformer. In my case this was a CSV transformer which was needed to test tabular data provided to…

docker

Secure Docker Grafana container with SSL through Traefik proxy

You are wondering how to auto-generate free and auto-renewable SSL certificate for you Grafana container? This was also my concern some time…

frontend

What is and how to use Google Tag Manager

Google Tag Manager (GTM) is a tool made by Google which lets you modify content of your website without touching its codebase. It adds a…

javascript

Electron opening link in a new window

Opening a link in a new window/tab is not a big deal when working with a regular single page application rendered inside browser. Usually…

react

React multiple event handlers performance

How to bind handlers in React to multiple similar elements e.g. buttons on list? Is it any better to use one handler and identify clicked…

react

React.PureComponent - different ways of writing event handlers

There are many ways to define event handlers in React. Are there any differences between them? TLDR; You should probably avoid the inline…

react

React.PureComponent - children vs custom properties

Can I use the property with React.PureComponent, or do I have to use only custom properties? TLDR; You can use with React.PureComponent as…

javascript

Integration tests with Jest, Selenium and BrowserStack - part 1 - simple example

Although there is much useful information on the official BrowserStack website, you will certainly have a lot of questions when you run…

backend

Traefik - proxy development server with self-signed SSL certificate

You want to check how (or if) your application works with SSL encryption without exposing it to the Internet? Use a self-signed SSL…

frontend

Integration tests with Jest, Selenium and BrowserStack - part 2 - multiple browsers

As described in part 1 you can run Jest based tests with BrowserStack service. Now I will show how they can be automatically run against…

javascript

Publishing NPM package with Rollup, Babel, Flow, Jest and ESLint

Here is a description of common tools and files used to create a modern NPM package. Don't hesitate to clone my npm-lib-package-boilerplate…

javascript

Time Series Admin - Electron-based alternative to Admin UI for InfluxDB

InfluxDB turns out to be a good solution for a time series data which happens to be the cornerstone of my current job. As (probably) every…

javascript

Flow type checking for Axios

Type checking with Flow is a nice addition to your code. Unfortunately, it is not so intuitive to use Flow with libraries like Axios. The…

vim

Using Vim or NeoVim as a Git mergetool

The "ugly" 4 window view of the default configuration can scare you out even if you were using Vim for a while. It's just too much…

javascript

ImmutableJS .toJS() vs .toArray()

General advice is to never convert data from Immutable to native JS types. But if you have to do it use rather than of course if you work…

backend

RabbitMQ amqplib - "Error: Channel closed by server: 406 (PRECONDITION-FAILED) with message "PRECONDITION_FAILED - unknown delivery tag 1"

If you are struggling with the 406 error message which is included in title of this post you may be interested in reading the whole story…

javascript

Running Jest tests with Flow typed Javascript files

This will be a simple tutorial about running Jest tests with Flow typed Javascript files in NodeJS project. Problem Recently I've started…

javascript

How to run Jest tests with Rewire plugin

Another Jest connected post. How to test internal module functions that are not exported? Problem I want to test internal function defined…

frontend

Ionic 3 show/hide content based on screen size

Here is a complete Bootstrap-like solution for showing and hiding selected Ionic components based on screen size. Go to solution…

frontend

Ionic 3 browser splash screen / preloader

The Splash Screen component is available for a long time but only as Ionic Native component, so we can't use it inside browser. I will…

tools

Duplicati backup filters configuration

Duplicati is a free backup tool which is my current choice for cloud backups. Why Some time ago I wrote a post about Restic which is a nice…

tools

Restic backups with Backblaze B2

How to create Restic based backup using Backblaze B2 cloud storage as a backend. This tutorial was made on Mac OS X High Sierra with restic…

frontend

Ionic Framework - ionic-app-scripts live reload shows old content

A solution for live reload "bug" while using ionic-app-scripts which causes showing old content after automatic page refresh. If you are…

javascript

graphql-yoga import .graphql files

It is possible to split you type definitions to multiple files and then merge them back using merge-graphql-schemas ensuring graphql…

frontend

Ionic 3 Framework - setFocus on opened modal input

Use Angular hook and execute inside it. While working with the Ionic 3 Framework I came across (as it turns out) popular problem of…

tools

Adding new partition to the existing Vagrant VM

This will be a tutorial about adding new partition to the existing Vagrant (Virtual Box) machine. It should be safe to follow but please…

javascript

Ionic Framework 3 - troubleshooting

While playing with Ionic Framework v3 I came across few errors/problems which I would like to describe here. ion-app did not match eny…

tools

Resizing existing VM partition

Use vagrant-disksize plugin from https://github.com/sprotheroe/vagrant-disksize Set required disk size Inside Vagrantfile Start Vagrant or…

tools

iOS simulator SSL certificates problems

iOS simulator is a handy tool available for every OS X user but you may encounter This Connection Is Not Private or other strange bugs when…

MongoDB + Letsencrypt + Docker

How to setup MongoDB Docker container to use Let's Encrypt SSL certificate with autorenewal support? That's something which should be much…

docker

Grafana and InfluxDB with Let's Encrypt SSL on Docker

Deprecation warning This is now deprecated! Please head to Secure Docker Grafana container with SSL through Traefik proxy which is far more…

hostings

DNS configuration to delegate only website to other hosting

That was the case in my recent project where a client wants to use his current hosting provider for email but generally, it was advisable to…

docker

Grafana Docker container and Google Analytics

How easy is adding Google Analytics support to Grafana Docker container? It's trivial. Just add an environment variable to the Grafana…

tools

Track file changes and automate script execution

Recently I came across an issue of "live" synchronization of my local files with a remote host. It was necessary to upload project files as…

docker

How to backup and restore InfluxDB which runs inside Docker container

Running InfluxDB inside Docker container is extremely easy with the official image available on Docker Hub https://hub.docker.com/_/influxdb…

tools

Monitor iPhone network traffic with Wireshark

Use and Wireshark. In order to user rvictl you have to have latest Xcode installed and launched at least once (during first run Xcode…

wordpress

Wordpress WMPL Post Type Switcher support

Adding WPML support to PostType Switcher plugin is easy. My solution is based on https://wordpress.org/support/topic/simple-hack-to-add-wpml…

wordpress

Wordpress Roots Sage 9 translations

Adding translations to the current Roots Sage version (which is 9.0.0-beta.4) is not as easy and standard as it was in previous versions…

wordpress

Roots Sage 9.0.0 - error Command failed with exit code 2

During assets compilation with , or you may run into this error: error Command failed with exit code 2 Workaround In order to fix it try…

php

PHP default values with array_merge

In PHP there is no option to provide default values for an associative array as an argument. E.g. (is not possible) In order to solve that…

wordpress

Wordpress rewrite rules and pagination

If you are making larger Wordpress site at some point you will definitely come across custom rewrite rules configuration. The tools (plugins…

meteor

Meteor node-simple-schema and Meteor.users collection

If you use Meteor you have to come across the node-simple-schema formerly known as . This is definitely a great package which eases data…

vim

Docker and Vdebug for PHP debugging

Docker is a great tool but unfortunately when you have a separate container for each web project you may start having issues with the…

tools

Free image sources for commercial and non-commercial use

Here is a list of popular pages which offers free images. By free images I mean CC0 (or similar) licensed pictures which may be used (and…

ruby

Ruby on Rails custom Capistrano tasks

Writing and using custom Capistrano tasks is very easy and automating your deployment process may save you a lot of time and troubles. Here…

vim

Docker with Xdebug a final guide with troubleshooting tips

After spending a nearly whole day fighting with Xdebug setup I think it is a right moment to write some complete Xdebug guide. In this…

docker

Docker for Mac OS X

This will be a set of questions and answers related to the Docker usage under OS X. Where are my Docker files? They are supposed to be…

tools

DNSmasq for custom development domain name

Setting up a custom domain name for a local development may be really useful especially when you want to test multisite setup (e.g. for…

tools

Vim registers - how to use Vim multiple clipboards feature

Using registers in Vim is like having a large number of clipboards where you can copy and paste from whenever you want. Here is how to use…

tools

Adding a CNAME record to the DNS

In order to check your current DNS records, you may use this tool https://www.samdns.com/ It allows you to specify DNS server, so you don't…

ios

iPhone 6s iOS 10.3.1 Unable to Verify Update

Recently I've tried to install the newest iOS 10.3.1 update on my iPhone. Unfortunately, instead of a successful installation, I was getting…

mac

Mac OS X upgrade - is it safe for your tools

Recently minimal system requirements of the new Sketch App 42 forces me to make an OS X upgrade. It turns out that upgrading to the not most…

mac

How to restore selected files from Time Machine backup

Don't ask me why I've made this post... If you accidentally delete half of your projects I hope you have a recent backup available. Even if…

wordpress

ACF PHP API the missing docs

The most useful feature of the ACF Wordpress plugin is its PHP API. Unfortunately, it is not fully documented on the official page. Here are…

ruby

Rails number_to_currency change locale defaults

ActiveSupport helper method may be extremely useful if you deal with prices/wages inside your app. By default uses your current locale…

wordpress

How to get list of all ACF fields?

Getting a list of all ACF fields may be useful e.g. if you want the user to select one of them as a data source. In my case, I needed that…

wordpress

Wordpress HTTP error when uploading a photo

I had a few cases when clients report an "HTTP error" during photo upload. Which looks similar to this: In all these cases the problem was…

rails

Rails 5 with PDF.js

Opening PDFs directly on the web page was one of the requirements for my recent project. The obvious choice was to use the PDF.js library…

vim

Vim regex examples

A list of Vim regex examples which might be useful for code/text refactoring. Not something (excluding some character) The regex below will…

tools

Useful Bash commands

This is a list of Bash commands that I frequently use with a short explanation. It may help you in everyday usage of your Unix based system…

rails

Generate PDF with Prawn gem in Rails 5 application

During my recent project development, I came across a problem of generating PDFs. Fortunately, there is a nice gem for creating PDF…

wordpress

Wordpress plugins

This is a list of useful Wordpress plugins which I use in my projects. Each plugin will have a short description in which I would try to…

javascript

ScrollMagic setup for Webpack (a CommonJS setup)

ScrollMagic is a great JS library which makes you page look lively. Here is how I manage to integrate it with my Webpack based build process…

ruby

Dry-validation custom error messages

While defining custom errors is described in the official documentation I had a few issues. Here are my findings. First of all integration…

ghost-tag

Adding code highlighting to Ghost blog

Running any kind of code related blog on the Ghost platform would eventually require adding some syntax highlighting to your code snippets…

wordpress

Use ACF image field as thumbnail input

Standard Wordpress thumbnail input may be replaced with an ACF image field which is far more flexible/customizable. In order to do that you…

javascript

Custom scrollbars for HTML elements

Sometimes your website may need inner scrolling for an element with overflowing content. In most cases using simple: is not enough to…

mac

Useful OS X Apps

This is a list of applications and utilities which I find most useful for my everyday tasks. Spectacle You can live without the Spectacle…

mac

Custom Mac OS X screenshots location and format

Default screenshots location on Macs is your Desktop which is not very convenient. After a few months, it will look (probably always) like…

ghost-tag

Hands on Ghost

WordPress is an obvious choice if you want to write your own online blog. It is especially true if you are a WordPress developer which…

ghost-tag

Setup Ghost blog on Mydevil.net

Ghost is an awesome blogging platform, but there is one "problem", it is written in Nodejs which is not so widely supported (as PHP) among a…

wordpress

Wordpess theme responsive images

Ensuring good responsive images support in Wordpress can be a quite complicated task. When you try to provide dedicated image size for each…