How to use the unit testing pattern Arrange Act Assert, and why the three As are so useful. Example of how to use arrange-act-assert with a JS function.

Solution for testing that images have rendered in React using Jest. And how to test an image alt and src in jest using React. Including example code.

How to mock a React component in a jest unit test. Example of how to mock a default or named component using React Testing Library.

Examples of how to use within in Jest and React Testing Library to target a specific section of the component. Restrict Jest queries to a particular element. Inside the context of a DOM node.

Using React MUI DatePicker dynamically lazy load date-fns locale files for localization. Reduce page size, speed up load time. Full working example and how to solution. Import locale files from date-fns.

Solution for error 'RangeError: timeZone is not supported.' when unit testing Intl API. Caused by Node not supporting time zones

Solution for 'warn chunk commons [mini-css-extract-plugin]' error in Gatsby JS error in log. Conflicting order warning.

Updating React Material UI Core causes error: 'Failed prop type: The prop `disableBackdropClick` of `ForwardRef(Dialog)` is deprecated' - SOLVED! With example.

Solution for adding media.net ad script to React website. Provides a React component for showing media.net adverts. Simple example of how to add script to a website.

Solution to YouTube videos/iframes negatively effecting website load speed. Use Intersection Observer API To Lazy Load. React component included in article.