401-class-28.md

Component Lifecycle / useEffect() Hook

Review, Research, and Discussion

1. Why do we not need more .html pages in a multi-page React app?
   • react app pages re-render to update with new content
2. If we wanted a component to show up on every page, where would we put it and why?
   • Inside the , because it is the parent router component so the component will render with all child components
3. What does routing do with the components that were rendered when a new route is requested
   • ignores the other components
4. What does props.children contain?
   • content between the opening and closing tags of the containing component
5. How do useState() and this.setState() differ?
   • for useState(), deconstruction is used to define the state's variable and updating function

Vocab Terms

• State Hook

  • can only be used inside function components, needs to be imported from react, lets you add state to function components, an initial value can be passed into the useState() parentheses
  • can declare a new state variable and function to update it via deconstruction:
    • const [count, setCount] = useState(0);
  • source: https://reactjs.org/docs/hooks-state.html

• Mounting and Un-Mounting

  • the useEffect() hook allows you to use side effects within function components
  • source: https://reactjs.org/docs/hooks-effect.html