Learn React with TypeScript 3

componentDidMount

componentDidMount is invoked when a component has been inserted into the DOM. Here are some common use cases for this method:

• Calling a web service to get some data
• Adding event listeners
• Initializing timers
• Initializing third-party libraries

We're going to change the app we have been building to give users a time limit of 10 seconds to confirm whether or not they want to learn React and TypeScript. In order to do this, we'll need to make use of the componentDidMount method:

1. Let's start by making the confirmation dialog closed when the app loads in App.tsx:

constructor(props: {}) {  super(props);  this.state = {    confirmMessage: "Please hit the confirm button",    confirmOpen: false  };}

2. We're going to count down the seconds ...