Inside a react component tree, componentDidMount() is fired after all children components have also been mounted. This means, that any component’s componentDidMount() is fired before its parent has been mounted. So if you want to measure DOM position and sizes etc, using componentDidMount() of a child component is an unsafe place/ time to do this. … Read more
React and ReactDOM were only recently split into two different libraries. Prior to v0.14, all ReactDOM functionality was part of React. This may be a source of confusion, since any slightly dated documentation won’t mention the React / ReactDOM distinction. As the name implies, ReactDOM is the glue between React and the DOM. Often, you … Read more
The goal When the html page is rendered, display a spinner immediately (while React loads), and hide it after React is ready. Since the spinner is rendered in pure HTML/CSS (outside of the React domain), React shouldn’t control the showing/hiding process directly, and the implementation should be transparent to React. Solution 1 – the :empty … Read more
StrictMode renders components twice (on dev but not production) in order to detect any problems with your code and warn you about them (which can be quite useful). If you have StrictMode enabled in your app but don’t remember enabling it, it might be because you used create-react-app or similar to create your app initially, … Read more