React Hook Form is a library for managing form state and validation in React applications using hooks. It is designed to make form handling in React applications more efficient and straightforward. React Hook Form is a popular alternative to other form management libraries like Formik.

Some of the key features and benefits of React Hook Form include:

1. Hooks-based: React Hook Form leverages React's hooks API, making it a natural fit for modern React applications. You can manage form state and validation rules using simple and familiar hooks.

2. Minimal Re-renders: The library is designed to minimize unnecessary re-renders, which can improve performance. It does so by only re-rendering form components when needed.

3. Validation: React Hook Form provides a flexible and extensible way to define and perform form validation. You can define validation rules for each input field and trigger validation at various points in the form submission process.

4. Custom Inputs: You can easily create and use custom form input components with React Hook Form, allowing you to encapsulate form logic and reusability.

5. Error Handling: The library provides mechanisms to handle and display validation errors, making it easier to provide feedback to users.

6. Optimized for Controlled Inputs: It primarily focuses on controlled input components, which helps you maintain full control over your form state and avoid common issues with uncontrolled components.

7. Built-in Support for Uncontrolled Components: While primarily designed for controlled inputs, React Hook Form also offers support for uncontrolled inputs when necessary.

8. Form Submission: React Hook Form provides methods for handling form submissions and managing form data, making it easier to integrate with your backend services.

RxWeather is one of my practice apps which fetches the weather from a free api using your location or you can enter a city name. I also displays a map zoomed in on the city. I built this as an example of a Typescript React application using redux-observable/RxJs and Mapbox. 

In case you have not heard of redux-observable, it is a middleware library for managing asynchronous operations and side effects in Redux applications. It enables you to handle complex asynchronous flows using reactive programming principles and techniques. The library is built on top of the popular RxJS library, which provides tools for working with asynchronous and event-driven code using Observables.

The primary goal of redux-observable is to provide a way to handle side effects in a more organized and maintainable manner while adhering to the principles of Redux. By using Observables, you can model and manage asynchronous actions, such as making API requests, handling user input, and managing timers, in a consistent and predictable way.

Key concepts of redux-observable include:

Epics: Epics are the core building blocks of redux-observable. They are functions that take a stream of actions as input and return a stream of new actions as output. Epics allow you to react to specific actions and perform asynchronous operations, transforming them into new actions.

Observables: Observables are streams of values that can be observed over time. In the context of redux-observable, Observables represent streams of actions and can be transformed using various operators from the RxJS library.

Actions and Action Creators: Just like in Redux, actions represent events or changes in your application. Action creators are functions that create action objects. In redux-observable, you can use actions to trigger epics and produce new actions.

I had some free time last Saturday, so I decided to play with d3.format() and created an AngularJS number filter for formatting numbers in common formats you might see on a website or application. This is what I came up with.

Just to be fair, I decided to make a React as well as an Angular 6 version too.

D3.js (Data-Driven Documents) is an open-source JavaScript library for creating dynamic and interactive data visualizations in web browsers. It allows developers to bind data to Document Object Model (DOM) elements and then apply data-driven transformations to create complex and customized visual representations of data.

Key features and concepts of D3.js include:

Data Binding: D3.js enables you to bind data to DOM elements, associating data values with visual elements like SVG shapes, HTML elements, or Canvas graphics.

Data-Driven Transformations: D3.js allows you to apply data-driven transformations to manipulate the visual properties of elements, such as position, size, color, and shape.

SVG and Canvas Support: D3.js works with Scalable Vector Graphics (SVG) and HTML Canvas, giving you flexibility in choosing the appropriate rendering technology for your visualizations.

Selections: D3.js provides a powerful selection mechanism that allows you to select, filter, and manipulate DOM elements based on data conditions.

Data Joins: D3.js supports data joins, where you can efficiently join data with existing DOM elements or create new elements based on data.

Transitions and Animations: D3.js allows you to create smooth transitions and animations to enhance the visual experience of your data visualizations.

Scales and Axes: D3.js provides scale functions to map data values to visual attributes, such as positioning data on axes or determining the size of elements.