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In this article, we will learn how to show a loader while the component is being lazily loaded.When the components are lazily loaded, it requires a fallback to be shown to indicate that the component is being loaded in the DOM.SyntaxExampleIn this example, we will build a Routing application that lazily loads the component and displays a loader while the component is being loaded lazily.App.jsximport React, { Suspense, lazy } from 'react'; import { BrowserRouter as Router, Route } from 'react-router-dom'; import Loader from './Loader.js'; const Contact = lazy(() => import('./Contact')); const App = () => ( ... Read More
In this article, we are going to see how to highlight potential problems that we might have in a React Application.React.StrictMode is a helper functionality provided by React which allows us to write better React codes. It provides visual feedback in the form of warnings if we don’t follow the React guidelines, but it works only in the development mode.Note: They are unsafe to use while using async await.Use-cases of Strict Mode −Identifying components with unsafe lifecyclesWarning about legacy string ref API usageWarning about deprecated findDOMNode usageDetecting unexpected side effectsDetecting legacy context APIWe can also bind React.StrictMode to work only ... Read More
In this article, we are going to learn how to send and receive Http Responses in a React application.To send or receive data, we don’t need to use third-party packages, rather we can use the fetch() method which is now supported by all the modern browsers.Sending GET requesthttps://jsonplaceholder.typicode.com/todos/1Jsonplaceholder is a fake API which is used to learn the process of sending requests.Exampleindex.jsximport React from "react"; import ReactDOM from "react-dom"; import { CookiesProvider } from "react-cookie"; import App from "./App"; ReactDOM.render( , document.getElementById('root') );App.jsximport React, { useEffect, useState } from 'react'; const ... Read More
In this article, we are going to see how to use the useState hook in a functional component.State is the place where the data comes from. We should always try to make our state as simple as possible. With React 16.8, hooks are released which allow us to handle the state with less coding.Syntaxconst [state, setState] = useState(initialstate)It accepts two parameters – state and setState. State is the current state, while setState is used to change the state of the functional component.On every state change, the component re-renders with the updated state.ExampleIn this example, we will build a React application ... Read More
In this article, we are going to see how to create a reference to any DOM element in a functional component.This hook is used to access any DOM element in a component and it returns a mutable ref object which will be persisted as long as the component is placed in the DOM.If we pass a ref object to any DOM element, then the .current property to the corresponding DOM node elements will be added whenever the node changes.Syntaxconst refContainer = useRef(initialValue);ExampleIn this example, we will build a React application that passes the ref object to two input fields.When clicked ... Read More
This hook is a better alternative of the useState hook, as it is used when we want to attach a function along with handling the state or when we want to handle the state based on the previous values.Syntaxconst [state, dispatch] = useReducer(reducer, initialArgs, init);ParametersReducer − The function to handle or update the stateinitialArgs − Iitial stateInit − To load the state lazily or when it is requiredExampleIn this example, we will build a simple calculator using the useReducer hook which takes the input from the user and displays the result accordingly.App.jsximport React, { useReducer } from 'react'; const ... Read More
In this article, we are going to see how to optimize a React application by passing a memoized value.This hook is used to optimize the React application by returning a memoized value which helps to prevent doing the complex calculations on every re-rendering. This hook stores the cached value and only updates the function on certain defined conditions.Note: Don’t call side-effects in useMemo hooks; use useEffect hook instead.Syntaxconst memoizedValue = useMemo(() => computeExpensiveValue(a, b), [a, b]);Here, the returned value of computeExpensiveValue() function will only be changed on the next re-render if the values of a or b change.Without useMemo HookExampleIn ... Read More
In this article, we are going to see how to set up side-effects or HTTP requests in a functional component.This hook has the similar functioning like that of useEffect hooks but rather than being called out asynchronously, it has a synchronous effect. This hook is used to load the data in the DOM synchronously and also works in the same phase like that of useEffect hook.Note: Use useLayoutEffect hook only if useEffect hooks don't give the expected output.SyntaxuseLayoutEffect()ExampleIn this example, we will build a React application that displays and updates the name synchronously.App.jsximport React, { useLayoutEffect, useState } from 'react'; ... Read More
In this article, we are going to see how to customize the instance value of the ref object.Both useImperativeHandle and useRef hook allows to pass the ref object but the latter one doesn’t allow to customize the instances that are also passed with the ref object. useImperativeHandle hooks is different from the useRef hook in majorly two ways −It allows handling and customizing the returned value explicitly.It allows you to replace the native instances of the ref object with the user-defined ones.SyntaxuseImperativeHandle(ref, createHandle, [deps])ExampleIn this example, we are going to build a custom Button Component that has a user-defined instance attached ... Read More
An array of structure in C programming is a collection of different datatype variables, grouped together under a single name.General form of structure declarationThe structural declaration is as follows −struct tagname{ datatype member1; datatype member2; datatype member n; };Here, struct is the keyword.tagname specifies the name of structure.member1, member2 specifies the data items that make up structure.ExampleThe following example shows the usage of array within a structure in C programming −struct book{ int pages; char author [30]; float price; };ExampleFollowing is the C program to demonstrate the use of an array within a structure ... Read More