Hands down, ReactJS is one of the most widely used frontend libraries for building the most user-friendly UIs.The world-renowned library enjoys global community support which further adds to its popularity. React js development company has its own USP. The library is especially good for building very intuitive and responsive UIs for your web or mobile applications. There are several ways in which React fosters its remarkable UI development features. React stands out for its virtual DOM and reusable components. These features let us design intricate user interfaces for our apps. As a result, ReactJS-based applications are incredibly responsive and easy to develop. JSX is another integration to React that allows it to build complex UIs at relative ease on the developer side.
However, you already know these if you are here to learn about JSX. There goes no place for assumptions that you have also heard about JSX. So without wasting any more words, let’s get to the core of this discussion. First, we begin with what is JSX after all.
JSX – JavaScript Syntax Extension, what is it?
A JavaScript extension in ReactJS called JSX, or JavaScript syntax extension.
JSX, as its primary function, enables us to define React’s object tree using syntax resembling that of an HTML template. JSX makes it possible to create markup-like JavaScript in ReactJS. Once this is done, all it takes is the use of an XML-like extension to have JSX returned from a component.
As you may already be aware, JSX tells React how our UI should appear. In other words, JSX makes it simpler for a developer to describe the components of any UI to ReactJS. You could compare it to a template language, but because JS fully supports it, it is considerably more powerful.
Why do we need JSX?
Now that we get what JSX is with a fair amount of comprehension, the question that arises next is why do we need JSX? This has got to be a question you might ask at this point. As I previously mentioned, we use JSX to get React to understand the components we want on our user interface. For front-end developers, this job is made simple and elegant using JSX. A few of JSX’s main advantages are as follows:
- Leaning on the help of JSX, React can now show more beneficial errors and warnings.
- If one is familiar with HTML, using JSX for developing React programs is relatively straightforward.
- According to the React website, the major population of developers finds it helpful as a visual aid when dealing with UI inside the JavaScript code.
- Compared to JavaScript standards, it is faster. This is due to optimizations made by JSX during the JavaScript conversion process.
- As I already mentioned, JSX also helps preserve consistency while writing large amounts of code.
JSX features in React
We must quickly go over two significant JSX in React features in this section. These are object representation and the prevention of injection attacks.
Avoiding Injection Attacks
JSX protects your program from XSS attacks. React DOM by default escapes all values encoded in JSX prior to rendering them. As a consequence, it ensures that there will never be anything injected that has not gotten expressly indicated in our application. Everything described in the elements is converted into a string before displaying. Attacks employing cross-site scripting (XSS) are therefore less likely. This enables us to incorporate user inputs into JSX securely.
const title = response.potentiallymaliciousinput;
// This is safe:
const element = <h1>{title}</h1>;
React gets JSX transpiled using Babel. JSX is transpiled into createElement() calls for React. Take into account the following two instances to better understand it. These are the same as each other.
const element = (
<h1 className=”greeting”>
Hello, world!
</h1>
);
and
const element = React.createElement(
‘h1’,
{className: ‘greeting’},
‘Hello, world!’
React.createElement() creates an object called React elements after running a few bug inspections. These might be taken as a straightforward explanation of what would be seen on the display. These objects are used by React to build DOMs. Click here to learn more about DOMs in ReactJS.
const element = {
type: ‘h1’,
props: {
className: ‘greeting’,
children: ‘Hello, world!’
}
};
Common DOM elements in React when working with JSX
React generates prompt and responsive UIs through virtual DOMs. React heavily relies on DOMs to create complex UIsThere are some commonly used DOMs used while working with JSX on React that enhance the performance of React. Here is a list of the DOMs you are most likely to need while using JSX on React:
- props: In React, they are the objects with properties that are supplied to the component; they are also known as null or “props” in other languages.
- children: The children we must pass into the elements are referred to by this term. When this is a quoted string, as was shown above, the information will be shown as text. We can nest many more children as we want by using an array to add a number of them.
- Keys are used to specifically identify entries from one another while mapping across arrays.
- type: The React element’s type can be defined to determine how it will be rendered using type. For this, you can use a string (“div,” “h1”), a React component (class or function), or a React fragment.
- reference: These are actual DOM node pointers. They give you instant access to a component instance or DOM element.
- $$typeof: The property $$typeof identifies an object as a React element. It helps protect from XSS attacks (cross-site scripting).
Let us now understand this a little better. Here we will note the DOMs used in the above-shown example. Note these elements from the above example:
const element = {
type: ‘h1’,
props: {
className: ‘greeting’,
children: ‘Hello, world!’
}
};
JSX at work in ReactJS
How about using examples to talk about working with JSX at a basic level?
The simplest known component, rendering “Hello World” in the display, is where we start.
This component seems to return HTML, but it does not. The Greet component generates a <h1> tag using React.createElement() signature JS function.
Expression Embedding
The variable must first be declared, and then it must be enclosed in curly braces before any legal JavaScript expression can be added. To make JSX easier to read, it is recommended to divide it into several lines.
To begin with, we will declare a variable for use in JSX. Call the variable by its name. This variable needs to be enclosed in curly braces.
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 take note that I segmented the JSX into multiple lines using parentheses. This prevents mistakes from being introduced by automatic semicolon insertion.
Even JSX itself qualifies as an expression. Expressions in JSX are transformed into calls to common Js functions. After compilation, they are then evaluated to create JavaScript objects.
It is quite important that JSX itself can be an expression. JSX has many uses, including in if statements, for loops, variable assignments, taking it as arguments, and the function returns. For instance:
function getGreeting(user) {
if (user) {
return <h1>Hello, {formatName(user)}!</h1>;
}
return <h1>Greetings to you.</h1>;
}
Defining Attributes
The initial section of a JSX tag specifies the type of the React element. String values are specified using quotes, and expressions are specified using curly brackets. It is not possible to specify both in one attribute.
Quotes are utilized as attributes when specifying string literals while curly braces are used to enclose Js expressions in an attribute, similar to (remember to not use quotes within curly braces).
Choosing children
The JSX language is a syntactic enhancer for the React function createElement (component, props, …children). We should utilize a self-closing form of tags, similar to XML if there are no children.
How do we then specify when there are children once that scenario has been covered? Look at the illustration below.
const element = (
<div>
<h1>Greetings to you</h1>
<h2>I am happy to see you here</h2>
</div>
);
React 17+ and JSX
Have you ever seen a JSX error that stated React must be in scope? React versions 17 and higher are free of this problem. This is so that JSX does not necessarily be in Scope, thanks to work done by Facebook and Babel to improve ReactJS. Let’s first examine how JSX functions with Scope before discussing how it can function without it.
Babel, a transpiler, and JSX work together in React 17+.
Let’s quickly review what transpilers are first. These happen to be compilers that transform one syntactic type into another. Examples of transpilers include Babel or TypeScript.
Because JSX is not authentic JavaScript, browsers cannot read it directly. We require a transpiler for this to convert it to React. createElement(). Therefore, we employ transpilers to compile JSX into a form that is compatible with browsers.
The fact that this occurs during the build step means that the browser is also unlikely to be aware that JSX was there. The browser is then supplied with a tree of objects that have been specified using the React API.
Additionally, some older browsers have trouble figuring out new JavaScript functions. Those included in ECMAScript 6, notably, are problematic. In these circumstances, transpilers are useful for converting ES6 to ES5.
React without Scope and JSX
As we just discussed, React compiles JSX by calling createElement(). We don’t have to implement this ourselves thanks to React in Scope, which is available in React 17 or higher. However, it is still possible to use JSX with React without Scope or top-level imports of the React library. As you may have probably guessed, we can accomplish this using either TypeScript or a transpiler like Babel (React recommends this).
This section had to be covered in this conversation. This is so that the functions mentioned under react/jsx-runtime and react/jsx-dev-runtime can only be read by the compiler transform. If you need to manually construct objects in our code, you can keep using React.createElement.
Conclusion
We received a thorough introduction to JSX and ReactJS’s use of it in this blog. We talked about JSX and its advantages before highlighting how JSX works with React. We discovered that in order for React to read JSX, it needs to be transpiled. Older versions of React require a transpiler even though more recent versions do not. Transpilers are also necessary for some specialized tasks. Frontend programming with React is more elegant and straightforward thanks to JSX. You should now be able to comprehend JSX better, and even start using it in React, I hope!
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