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To detect when the Esc key is pressed in React.js: Add a keydown event listener to the document element. When the user presses a key, check if the key is Esc. If the key pressed is Escape, call a function or run some logic. import {u...

To check if a browser tab has focus using React: Add event listeners for the focus and blur events. If the focus event is fired, the tab has focus. If the blur event is fired, the tab loses focus. import {useE...

To delete query parameters using React Router: Use the useSearchParams hook to get the search parameters for the current location. Use the delete() method to delete each query parameter, such as searchParams.delete('q'). To update the search parameter...

In React, we use the String() function to render boolean values ​​in JSX, for example, h2{string(bool1)}/h2 . By default, boolean values ​​don’t render anything in React, so we have to convert the value to a string in order to render it. exp...

To create an input field in React.js that only contains numbers: Set the input field's type to text . Add an onChange event handler that removes all non-numeric values ​​. Save the input value in a state variable. import { useState } from reactjs...

To get the mouse position in React: Set the `onMouseMove` property on the element or add an event listener on the window object. Provide an event handler function. Access the relevant properties of the event object....

To get the value of an input when the Enter key is pressed in React: Set the onKeyDown property on the input field. When the user presses a key, check if that key is Enter. Access the value of the input field from a state variable. import { useState }...

To check if an element is in the Viewport in React.js: Set a ref attribute on the element. Use the IntersectionObserver API to track if elements intersect. App.js import {useEffect, useRef, useState, useMemo} from react ; export default function...

Add an event listener to the body element: Access the body element on the document object. Use the addEventListener() method on the body element in the useEffect hook. Remove the event listener when the component unmounts. import {useEffect} from reac...

Use square bracket notation to set and access state in React using dynamic keys, for example, setEmployee({...employee, [key]: employee.salary + 100}) . The variable or expression in the square brackets will be evaluated before setting the state. impo...

To change the style of an element using ref in React: Set the ref attribute on the element. Access the element through the current attribute on the ref. Update the element's style, for example ref.current.style.backgroundColor = green . import { useRe...

To get the height of an element using ref in React: Initialize a state variable that will store the element's height. Update the element's height in the useEffect() hook. The height should be set to ref.current.clientHeight . import {useEffect, useSta...

To pass a boolean value as props to a component in React, wrap the boolean value in curly braces, e.g. Child bool={true} / . All non-string props that we pass to a component must be enclosed in curly braces. function Child ( {bo...

React refs most often return undefined or null when we try to access their current properties before the corresponding DOM element is rendered. To fix this, you need to access the ref in the useEffect hook or when an event is triggered. import {useRef...

Unexpected default export of anonymous function warning is caused when we try to export an anonymous function using default export. To fix the error, name the function before exporting it. Below is a sample code Header.js that produces the above error...