React.js

Question 1

What is a React component?

Answer 1

independent and reusable bits of code.

They serve the same purpose as JavaScript functions, but work in isolation and return HTML via a render() function.

Question 2

How do you define a function component in React?

Answer 2

function functionName(props) {
  return (
    jsx;
  );
}

Question 3

How do you mount a component to the DOM?

Answer 3

ReactDOM.render(element, container)
element is a component ex)
container is usually a div with root

Question 4

What are props in React?

Answer 4

“Props” is a special keyword in React, which stands for properties and is being used for passing data from one component to another.

Question 5

How do you pass props to a component?

Answer 5

Use it as a parameter in the function component

Question 6

How do you write JavaScript expressions in JSX?

Answer 6

In curly braces

Question 7

How do you create “class” component in React?

Answer 7

class componentName extends React.component {
  render() {
    return { this.props.text };
  }
}

Question 8

How do you access props in a class component?

Answer 8

this.props

Question 9

What is the purpose of state in React?

Answer 9

To update state and change UI (re-render) accordingly

Question 10

How do you pass an event handler to a React element?

Answer 10

{ this.state.isClicked ? ‘Thanks!’ : ‘Click Me!’}