Class2
React lifecycle
- Based off the diagram, what happens first, the ‘render’ or the ‘componentDidMount’?
“render” happens before “componentDidMount”.
- What is the very first thing to happen in the lifecycle of React?
The cycle begins with the Mounting phase which begins with the Constructor function.
- Put the following things in the order that they happen: componentDidMount, render, constructor, componentWillUnmount, React Updates.
- constructor.
- render.
- componentDidMount.
- React Updates.
- componentWillUnmount.
- What does componentDidMount do?
This method is invoked immediately after a component is mounted. If you need to load anything using a network request or initialize the DOM, it should go here.
setState() can be called here, but it should be used sparingly, because it will cause a rerender, which can lead to perfomance issues.
State Vs Props
- What types of things can you pass in the props?
React allows us to pass values from a parent component down to a child component. The values can be any data type, from strings to functions, objects, etc.
- What is the big difference between props and state?
Props is an object of arbitrary inputs a React function component accepts as the first argument.
State is data that changes over the lifetime of a specific instance of a React component.
- When do we re-render our application?
React components automatically re-render whenever there is a change in their state or props
- What are some examples of things that we could store in state?
We use state for storing any data which may be a string, number or any complex object.