What is StrictMode in react?

Question

I heard that strict mode helps to write React code in best practices way by throwing warnings for life cycle methods removal.

I read about it from https://medium.co

Answer 1

Warning: StrictMode will render the components twice only on the development mode not production.

For instance, if you're using getDerivedStateFromProps method like so

   static getDerivedStateFromProps(nextProps, prevState){// it will call twice
        if(prevState.name !== nextProps.name){
            console.log(`PrevState: ${prevState.name} + nextProps: ${nextProps.name}`) 
            return { name: nextProps.name }
        }
        return {}
    }

The getDerivedStateFromProps method will call twice.

Just to let you know this is not a problem, it's just because you're wrapping your main component with in the index.js file.

StrictMode renders components twice in order to detect any problems with your code and warn you about them.