react

What is the second argument for setState useful for?

• To invoke code after the setState operation is done

• To replace the state completely instead of the default merge action

• To access the previous state before the setState operation

• None of the above

How do you invoke setDone only when component mounts, using hooks?

• useEffect(() => { setDone(true);

  });

• useEffect(() => { setDone(true);

  }, []);

• useEffect(() => { setDone(true);

  }, [setDone]);

• useEffect(() => { setDone(true);

  }, [done, setDone]);

Which Hook could be used to update the document's title?

• useEffect(function updateTitle() { document.title = name + ' ' + lastname; });

• useEffect(() => { title = name + ' ' + lastname;

  });

• useEffect(function updateTitle() { name + ' ' + lastname;

  });

• useEffect(function updateTitle() {

  title = name + ' ' + lastname;

  });

Will useEffect affect other data?

• True

• False

If a function component should always render the same way given the same props, what is a simple performance optimization available for it?

• Wrap it in the React.memo higher-order component.

• Implement the useReducer Hook.

• Implement the shouldComponentUpdate lifecycle method.

• Implement the useMemo Hook.

When do you use useLayoutEffect?

• to optimize for all devices

• to complete the update

• to change the layout of the screen

• when you need the browser to paint after the effect runs

Why might you use useReducer over useState in a React component?

• when you have complex state logic that involves multiple sub-values

• when you want to break your production app

• when you like =)))

• can not be replaced

If you see the following import in a file, what is being used for state management in the component?

import React, {useState} from 'react'; 

• stateful components

• class components

• math

• React Hooks

How do you handle passing through the component tree without having to pass props down manually at every level?

• React Send

• React Pinpoint

• React Router

• React Context