devBlog of Michal Zalecki

Fixtures, the way to manage sample and test data

Fixtures are a thin abstraction layer over sample data in your application which allows for better organizing, often complex, data structures representing different entities. If this sounds like a vague description or does not ring the bell maybe an example will speak to you better.

Creating a TypeScript library with a minimal setup

There are a few major reasons due to which you may find yourself creating a library. One, obviously, is that you have a solution which you would like to share with the Open Source community. The other one is that you need to reuse code across different projects or in the same project but on different platforms.

Render React portals on the server

React works, in what I would call, homogeneous manner. A tree of components is going to be rendered in the given component using a render or recently introduced hydrate function. You are not supposed to change DOM elements created by React or at least do not change components which can return true from shouldComponentUpdate. But what if you need to change an element outside of the React realm? Well, portals are the way to go!

Writing clean code with memoized event handlers

When we talk about writing asynchronous JavaScript we often use timer functions or promises as an example. Whereas the majority of asynchronous code written in modern JavaScript web apps is focused on events caused either by a user interacting with the UI (addEventListener) or some native API (IndexedDB, WebSocket, ServiceWorker). With modern front-end frameworks and the way we pass event handlers it is easy to end up with leaky abstraction.

Optimize React build for production with webpack

This guide is a form of writing down few techniques that I have been using with ups and downs for the past two years. Optimizations highly depend on your goals, how users are experiencing your app, whether you care more about time to interactive or overall size. It should not come as a surprise, that like always, there is no silver bullet. Consider yourself warned. Although you have to optimize for your use cases, there is a set of common methods and rules to follow. Those rules are a great starting point to make your build lighter and faster.

Converting DOCX to PDF using Python

When you ask someone to send you a contract or a report there is a high probability that you’ll get a DOCX file. Whether you like it not, it makes sense considering that 1.2 billion people use Microsoft Office although a definition of “use” is quite vague in this case. DOCX is a binary file which is, unlike XLSX, not famous for being easy to integrate into your application. PDF is much easier when you care more about how a document is displayed than its abilities for further modifications. Let’s focus on that.

Implementing Geofencing with HERE

Geofencing allows for locating points within defined geographic areas. Areas can be defined with geographic points, consisting of latitude and longitude, forming any shape. HERE provides Geofencing Extension API for that purpose.

The Best React Boilerplate: DIY

I know, I know. This title sounds cocky. In fact, it makes a lot of sense if you think about it. I have been asked multiple times by my friends from our local React meetup group I am organizing or by teams I am helping to develop their applications for a starter, boilerplate or a setup. This post is a result of another such question. Most of the time it is one of the two scenarios.

Why using localStorage directly is a bad idea

If you are working on web services for some time you probably remember, or at least heard about, The First Browser War. We are extremely lucky that this scramble between Internet Explorer and Netscape turned into a great race for better, faster, more unified web experience. That said, we’re still facing a lot of inconsistency or not trivial edge cases while working with so-called browser APIs.

React components and class properties

React components went the long way from React.createClass through ES2015 powered React.Component to React.PureComponent and stateless functional components. I really enjoy the idea that we don’t have to “hack” the language anymore, at least not that much as we used to. The progress in this department is quite clear and brings not always obvious benefits. Using constructs built into the language/transpiler instead of relying on framework’s factory functions or constructors accepting huge configuration objects future proofs your code.

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