Billionaire Bucks Interview Questions and Answers

Answer to a React Developer interview question about class and functional components and passing props.

• Class component: class MyComponent extends React.Component {}

• Functional component: const MyComponent = (props) => {}

• Passing props from parent to child:

Export types in ReactJS allow components, functions, and variables to be accessed and used in other files.

• Exporting a component allows it to be imported and used in other files

• Exporting a function allows it to be imported and used in other files

• Exporting a variable allows it to be imported and used in other files

Hooks are functions that allow you to use state and other React features without writing a class.

• useState is a hook that allows you to add state to functional components.

• useEffect is a hook that allows you to perform side effects in functional components.

• Hooks can only be used in functional components.

• Hooks must be called at the top level of a functional component.

• Hooks can be used to replace lifecycle methods in class components.

Promises are a way to handle asynchronous operations in JavaScript. Promise.all is used to execute multiple promises concurrently.

• Promises represent a value that may not be available yet

• They have three states: pending, fulfilled, and rejected

• Promise.all takes an array of promises and returns a new promise that resolves when all promises in the array have resolved

• If any promise in the array is rejected, the returned promise is rejected with the reason of the first promise that...read more

The 'this' keyword in JS refers to the object that is currently executing the code.

• The value of 'this' depends on how a function is called.

• In a method, 'this' refers to the object that the method belongs to.

• In a regular function, 'this' refers to the global object (window in a browser).

• In an event handler, 'this' refers to the element that triggered the event.

• The value of 'this' can be explicitly set using call(), apply(), or bind() methods.

ES6 features: Spread Operator, Rest Parameter, Object Destructuring

• Spread Operator: allows an iterable to be expanded into individual elements

• Rest Parameter: allows a function to accept an indefinite number of arguments as an array

• Object Destructuring: allows extracting properties from an object and assigning them to variables