A crucial benefit of React that makes it possible to create rich user interfaces on the developer side is JSX. JSX is a syntax extension of Javascript that enables JavaScript to resemble HTML, referred to as XML.
Undoubtedly, one of the most popular frontend libraries used by any react development company for creating the most user-friendly UIs is ReactJS.
The support of the international community furthers the appeal of the acclaimed library. The USP of a ReactJS development company is unique.
The library is particularly handy for creating UIs for your web or mobile applications that are incredibly responsive and intuitive. React promotes its impressive UI development features in a number of different ways. React is unique because of its reusable components and virtual DOM.
We can create complex user interfaces for our programs because of these features. Applications built with ReactJS as a result are very responsive and simple to create.
But if you came here to discover JSX, you already know these. There is no room for inferences that you are also familiar with JSX. So let’s cut to the chase and explore the main points of this debate without further ado. We start by defining what JSX actually is.
What is JSX?
JSX, or JavaScript syntax extension, is a JavaScript extension in ReactJS.
The main purpose of JSX is to allow us to define the object tree of React using syntax similar to that of an HTML template. ReactJS allows for the creation of JavaScript that resembles HTML. After that, all it requires to get JSX back from a component is to use an XML-like extension.
As you probably know, JSX instructs React on how to display our UI. In other terms, JSX streamlines the developer’s ability to specify the elements of any UI in terms of ReactJS. It is comparable to a template language, but it is much more robust because JS completely supports it.
Why is JSX necessary?
The next question that emerges is, “Why do we need JSX?” Now that we understand what JSX is to a decent extent. You might fairly pose this question at this time. As I just said, we use JSX to teach React what elements we want on our user interface. This task is made easy and stylish for front-end developers via JSX.
Here are a number of JSX’s primary benefits:
- React may now display more helpful errors and warnings thanks to JSX.
- Using JSX for creating React apps is rather simple if you are familiar with HTML.
- The majority of developers find it useful as a visual aid when working with UI inside the JavaScript code, per the React website.
- It is quicker than JavaScript standards. This is because JSX during the JavaScript conversion process performed optimizations.
- As I’ve already stated, JSX also aids in maintaining consistency when writing a lot of code.
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ReactJS and JSX
In this part, we shall briefly go over two key JSX in React capabilities. They are the representation of objects and the defense against injection attacks.
Preventing Injection Attacks
Your program is shielded from XSS attacks by JSX. By convention, React DOM isolates each value encoded in JSX before rendering it. As a result, it guarantees that there will be nothing injected that hasn’t been explicitly mentioned in our application.
Before being shown, every description contained in the elements is transformed into a string. Cross-site scripting (XSS) attacks are thus less frequent. This makes it possible for us to safely include input from users into JSX.
const title = response.potentiallymaliciousinput;
// This is safe:
const element = <h1>{title}</h1>;
Babel is used for translating JSX for React. React createElement() calls are translated from JSX. For a better understanding, consider the next two examples. These two are identical to one another.
const element = (
<h1 className=”greeting”>
Hello, world!
</h1>
);
and
const element = React.createElement(
‘h1’,
{className: ‘greeting’},
‘Hello, world!’
After performing a few bug checks, React.createElement() generates an object referred to as React elements. These might be interpreted as a clear description of what will be displayed. React uses these objects to construct DOMs.
const element = {
type: ‘h1’,
props: {
className: ‘greeting’,
children: ‘Hello, world!’
}
};
Frequent DOM components when using JSX with React
Using virtual DOMs, React creates quick and responsive user interfaces. To build complex user interfaces, React strongly relies on DOMs. The efficiency of React is improved by a few frequently used DOMs while working with JSX. The following is a list of the DOMs you will probably require while using JSX on React:
- Props, also referred to as null or “props” in other languages, are the objects having properties that are delivered to the component in React.
- Children refer to the children that we must release into the elements. The details will be displayed as text when this is a quoted string, as was demonstrated above. Using an array to add a number of children allows us to nest as many more as we desire.
- When mapping across arrays, keys are needed to specifically distinguish elements from one another. When mapping across arrays, keys are employed to specifically distinguish elements from one another.
- The type of a React element can be specified to specify the way it has to be rendered. A string (“div,” “h1”), a React component (class or function), or a React fragment can all be used for this.
- Reference are actual pointers to DOM nodes. They provide immediate access to a DOM element or component instance.
- Property $$typeof is a React element identified by the $$typeof keyword. It provides defense against XSS assaults (cross-site scripting).
Let’s further our understanding of this immediately. The DOMs used in the example above will be noted here. Observe the following details from the case above:
const element = {
type: ‘h1’,
props: {
className: ‘greeting’,
children: ‘Hello, world!’
}
};
How JSX works in ReactJS
How about providing examples to speak about dealing with JSX at a basic level?
We begin with the easiest known component, which displays “Hello World” on the screen.
Although it appears to return HTML, this component does not. A <h1> tag is generated by the Greet component using React.createElement() identity JS function.
Any valid JavaScript expression cannot be added before the variable has been declared and is enclosed in curly braces. It is advised to break up JSX into multiple lines to make it easier to read.
We will first establish a variable to be used in JSX. Give the variable its proper name. Curly braces must be used to contain this variable.
const name = ‘Sam Stardust’;
const element = <h1>Hello, {name}</h1>;
By using the formatName(user) JS function, we can now incorporate the output of this expression into a <h1> element.
function formatName(user) {
return user.firstName + ‘ ‘ + user.lastName;
}
const user = {
firstName: ‘Sam’,
Lastname: ‘Stardust’
};
const element = (
<h1>
Hello, {formatName(user)}!
</h1>
);
Please note that I used parenthesis to divide the JSX into several lines. This stops the automatic insertion of semicolons from making mistakes.
In fact, JSX itself is an expression. Calls to popular Js functions are converted from JSX expressions. They are subsequently evaluated to produce JavaScript objects after compilation.
The fact that JSX itself can be an expression is crucial. In addition to being used in if statements, for loops, variable assignments, taking it as parameters, and function returns, JSX has many other applications. For illustration:
function getGreeting(user) {
if (user) {
return <h1>Hello, {formatName(user)}!</h1>;
}
return <h1>Greetings to you.</h1>;
}
Establishing Attributes
The type of the React element is specified in the first portion of a JSX tag. Expressions are expressed using curly brackets, while string values are specified using quotes. Both cannot be specified in a single attribute.
When defining string literals, quotes are used as attributes, but curly brackets are used to encapsulate Js expressions in a property, comparable to (remember to not use quotes within curly braces).
Selecting children
The React function createElement is enhanced syntactically by the JSX language (component, props, …children). If there are no children, we should use a self-closing version of tags, similar to XML.
After covering that scenario, how do we then define when there are children? Look at the example below.
const element = (
<div>
<h1>Greetings to you</h1>
<h2>I am happy to see you here</h2>
</div>
);
JSX in React 17+
Have you ever run into a JSX error that demanded React be included? Versions of React 17 and later are clear of this issue. Due to the work done by Facebook and Babel to enhance ReactJS, JSX need not necessarily be in scope. Before exploring how JSX can function without Scope, let’s first look at how it works with it.
In React 17+, JSX and a transpiler called Babel work together.
First, let’s quickly go over what transpilers are. In fact, these are compilers that change one syntactic type into another. Babel or TypeScript is a couple of examples of transpilers.
Browsers cannot read JSX directly since it is not genuine JavaScript. For this to be transpiled into React, we need a transpiler. createElement(). In order to translate JSX into a format that is compatible with browsers, we use transpilers.
Since this happens during the build phase, it is also unlikely that the browser will be aware that JSX was there. A tree of objects that have been defined using the React API is subsequently provided to the browser.
Furthermore, certain outdated browsers struggle to understand new JavaScript features. Particularly those present in ECMAScript 6 pose difficulties. Transpilers are helpful in these situations for converting ES6 to ES5.
JSX in React without Scope
React compiles JSX by invoking create elements like we just discussed (). React in Scope, a feature available in React 17 or higher, means we don’t have to carry out this implementation ourselves.
But even without Scope or top-level imports of the React library, JSX can be used with React. We may achieve this with TypeScript or a transpiler like Babel, as you may have predicted (React recommends this).
This discussion had to cover this area. This is done so that only the compiler transform may read the functions listed under-react/jsx-runtime and react/jsx-dev-runtime. You can continue to use React.createElement in our code if you wish to manually construct objects.
Conclusion
This article gave us a comprehensive guide to JSX and how ReactJS makes use of it. Before demonstrating how JSX integrates with React, we discussed JSX and its benefits. We found that JSX needs to be transpiled in order for React to read it. While more recent versions of React do not, older versions do require a transpiler. Additionally required for some specific activities are translated. Thanks to JSX, front-end programming with React is more streamlined and elegant. Now that you’ve learned more about JSX, you should be able to use it in React.
