Tuesday, August 3

Tag: React.js

React

React Integration Testing: Greater Coverage, Fewer Tests

Integration tests are a natural fit for interactive websites, like ones you might build with React. They validate how a user interacts with your app without the overhead of end-to-end testing.This article follows an exercise that starts with a simple website, validates behavior with unit and integration tests, and demonstrates how integration testing delivers greater value from fewer lines of code. The content assumes a familiarity with React and testing in JavaScript. Experience with Jest and React Testing Library is helpful but not required.There are three types of tests:Unit tests verify one piece of code in isolation. They are easy to write, but can miss the big picture. End-to-end tests (E2E) use an automation framework — such as Cypress or Selenium — to interact with your s...
React

Using Formik to Handle Forms in React

There is no doubt that web forms play an integral role in our web site or applications. By default, they provide a useful set of elements and features — from legends and fieldsets to native validation and states — but they only get us so far when we start to consider the peculiarities of using them. For example, how can we manipulate the state of a form? How about different forms of validation? Even hooking a form up to post submissions is a daunting effort at times.Component-driven front-end libraries, like React, can ease the task of wiring web forms but can also get verbose and redundant. That’s why I want to introduce you to Formik, a small library that solves the three most annoying parts of writing forms in React:State manipulation Form validation (and error messages) Form ...
Props and PropTypes in React
CSS Tricks, Web Tricks

Props and PropTypes in React

React encourages developers to build by breaking a UI up into components. This means there will always be a need to pass data from one component to another — more specifically, from parent to child component — since we’re stitching them together and they rely on one another.React calls the data passed between components props and we’re going to look into those in great detail. And, since we’re talking about props, any post on the topic would be incomplete without looking at PropTypes because they ensure that components are passing the right data needed for the job.With that, let’s unpack these essential but loaded terms together.  Props: The data being passed around Basically, props are what make React the tool that it is. React was designed to break things down into pie...
Finite State Machines with React
CSS Tricks, Web Tricks

Finite State Machines with React

As JavaScript applications on the web have grown more complex, so too has the complexity of dealing with state in those applications — state being the aggregate of all the data that an application needs to perform its function. Over the last several years, there has been a ton of great innovation in the realm of state management through tools like Redux, MobX, and Vuex. Something that hasn’t gotten quite as much attention, though, is state design.What in the heck do I mean by state design? Let’s set the scene a little bit. In the past, when building an application that needs to fetch some data from a backend service and display it to the user, I’ve designed my state to use boolean flags for various things like isLoading, isSuccess, isError, and so on down the line. As this...
Web Tricks

Build Custom Pagination with React

  Often times, we get involved in building web apps in which we are required to fetch large sets of data records from a remote server, API or some database sitting somewhere. If you are building a payment system for example, it could be fetching thousands of transactions. If it is a social media app, it could be fetching tonnes of user comments, profiles or activities. Whichever it is, there are a couple of methods for handling the data such that it doesn't become overwhelming to the end-user interacting with the app.One of the popular methods for handling large datasets on the view is by using the infinite scrolling technique - where more data is loaded in chunks as the user continues scrolling very close to the end of the page. This is the technique used in displaying search re...
CSS Tricks, Web Tricks

Managing State in React With Unstated

  As your application becomes more complex, the management of state can become tedious. A component's state is meant to be self-contained, which makes sharing state across multiple components a headache. Redux is usually the go-to library to manage state in React, however, depending on how complex your application is, you might not need Redux.Unstated is an alternative that provides you with the functionality to manage state across multiple components with a Container class and Provider and Subscribe components. Let's see Unstated in action by creating a simple counter and then look at a more advanced to-do application.Using Unstated to Create a CounterThe code for the counter we’re making is available on GitHub:View RepoYou can add Unstated to your application wi...