Q121. How do you enable custom fonts in Next.js?
By using the next/font package to optimize and load custom fonts. ```js import { Inter } from "next/font/google"; const inter = Inter({ subsets: ["latin"] }); export defa...
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Q122. What is a promise?
A **Promise** is a JavaScript object that represents the eventual completion (or failure) of an asynchronous operation and its resulting value. It acts as a placeholder f...
Q123. How do you configure Webpack in Next.js?
By adding a custom webpack configuration in next.config.js. ```js module.exports = { webpack: ( config, { buildId, dev, isServer, defaultLoaders, webpack } ) => { // Note...
Q124. Why do you need a promise?
Promises are **used to handle asynchronous operations**, especially in languages like JavaScript, which often work with non-blocking operations such as network requests, ...
Q125. Why should component names start with capital letter?
If you are rendering your component using JSX, the name of that component has to begin with a capital letter otherwise React will throw an error as an unrecognized tag. T...
Q126. How do you configure a custom Babel setup in Next.js?
By default, Next.js uses the high-performance Rust-based **SWC compiler**, which is up to 17x faster than Babel. However, if your project relies on legacy custom Babel pl...
Q127. Explain the three states of promise?
Promises have three states: 1. **Pending:** This is an initial state of the Promise before an operation begins 2. **Fulfilled:** This state indicates that the specified o...
Q128. Are custom DOM attributes supported in React v16?
**Note:** This question references React v16, which is outdated. The information below applies to React 16+, including current versions (React 18/19). Yes. Starting with ...
Q129. What is the purpose of next-env.d.ts?
**`next-env.d.ts`** is an auto-generated TypeScript declaration file placed at the root of a Next.js project. ### What It Does: It contains TypeScript reference directive...
Q130. What is a callback function?
A callback function is a function passed into another function as an argument. This function is invoked inside the outer function to complete an action. Let's take a simp...