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#Redux interview questions how to
#Redux interview questions update
#Redux interview questions code

Calls to setState() are asynchronous and may be batched ¹ ².When state changes, the component responds by re-rendering.

#Redux interview questions update

setState() schedules an update to a component’s state object.What does setState() do and how does it work? (B) forceUpdate() (and that it should be avoided!)ĥ.A re-render of the parent which may entail new Props.state is the JavaScript object, managed within the Component, that holds its internal state.props is immutable by the receiving Component.props is the JavaScript object, passed into a Component, that holds the configuration properties ¹.Further reading: How Are Function Components Different from Classes?.

#Redux interview questions code

Class lifecycle methods split up related pieces of code ⁴.Classes lead to a bulky hierarchy tree, especially during code reuse, which results in performance decreases and difficulty testing ³.Classes add unnecessary confusion for the sake of syntactic sugar ².Older third-party libraries might not be compatible with hooks yet.There are no Hook equivalents yet for the uncommon life cycles: getSnapshotBeforeUpdate and componentDidCatch.In the past, stateful and life cycle logic could only be incorporated in class components.With React Hooks, class components are replaceable with function components for the majority of use cases ¹.How do Class components compare with Function components? Function Component: Component implemented by a JS function that takes a props argument and returns a React elementĢ.Class Component: Component implemented using ES6 Classes extending React.Component.Component: an independent reusable piece of the UI.What is a Component in React and what are the two main ways to define them ? Further Reading: Reconciliation, Inside Fiber: in-depth overview of the new reconciliation algorithm in React, Virtual Dom is Pure Overheadġ.

#Redux interview questions how to

The updated virtual DOM is compared with its previous version using React’s ‘ diffing’ algorithm to determine how to best update the real DOM

Expected changes are first reflected in an updated version of the Virtual DOM.

Virtual DOM: React makes a virtual representation of the actual DOM in memory.

Manipulating the actual DOM is expensive.

(B) Safer code as the usage of JSX prevents XSS attacks ¹.

Babel compiles JSX into React.createElement() calls.

JSX is a Javascript syntax extension that allows us to write HTML in our JavaScript to create React Elements.

React is a JavaScript library for building user interfaces.

These questions show a basic grasp of what React is and how it works:

Further Readings: More In-depth Reading.

bullets will occasionally end in a citation or relevant article link ¹.

Questions often are linked to a page with an overview of the subject This sheet also only covers a basic overview, it doesn’t go in-depth of the inner workings or practical applications of React that may very well be required for more experienced positions. Please refer to those for a more thorough explanation. As such, I have included my citation links throughout most questions. One main purpose of this page is to redirect users to great sources containing answers and further readings for said questions. Please Note Before Reading: These answers are meant as quick references/ light refreshers and are not comprehensive explanations or tutorials. I try my best to adhere as closely to React source documentation as possible but if you see anywhere that information can be better summarized please let me know.

This page aims to aggregate multiple basic React interview questions in a succinct and unopinionated manner.