Also note the absence of the render() method. Rule Options. — To be able to use a component later, you need to first export it so you can import it somewhere else: The simplest way to define a component is to write a JavaScript function:This function is a valid React component because it accepts a single “props” (which stands for properties) object argument with data and returns a React element. Maybe you’re building a reusable component library, you want some components that output standard HTML elements with some logic defined by props. Introducing Memoizing with React.memo. In the below example the child component will take one property that is userName based on that we can show the userName in the UI otherwise we will show Guest instead of the userName. We often call the functional components as a stateless component because we doesn’t have any state here. For starters, we make it in a way that it displays a certain entity – posts. When creating components in React, there are two options: class components or functional components. Two types of React components A React component can be declared either as a function or as a class. Click this link to know more about the components. Take for example an component from … See line 29 of the code below. We can pass any kind of data in properties like a number, string, array, object, etc. This component is also a React function component of type Budget. For example: function LinkComponent(props) {const {children, disabled ... We have a functional component named Counter. Let's learn about a React Function Component with props. Click this link to know more about the components. The above 4 steps will successfully create a react functional component. The header alw… In general we will create the function name with first letter as a capital letter in react. Using a class component means your component will automatically have the idea of state, as well as component lifecycle methods. React.memo() is a higher-order component. To accept properties, a functional component accepts an argument, as in Listing 3. Prior to React 0.14, writing a presentational component (that is, one that just renders props, and doesn't have state), could be fairly verbose: Now, we can’t call it a stateless component anymore since it can also have states and lifecycles. Enough theory — let’s see this in practice! We can pass any kind of data in properties like a number, string, array, object, etc. In step 1: we are importing the react library to use all the react features that are applicable for the functional components. const functionalComponent = React.memo(function functionalComponent(props) { /* render using props */ }); We have wrapped the component inside the memo method. React.memo is a higher order component. by Evelyn Chan. It’s that simple. Like said before we can’t use the state in stateless components. React and TypeScript: The Unofficial Documentation. We use it as a callback function to the click event of a