5.4 Using JS Expressions in JSX · React Enlightenment [DRAFT] (2024)

FAQs

How to use JavaScript expressions in JSX? ›

Embedding Expressions in JSX

You can put any valid JavaScript expression inside the curly braces in JSX. For example, 2 + 2 , user.firstName , or formatName(user) are all valid JavaScript expressions. In the example below, we embed the result of calling a JavaScript function, formatName(user) , into an <h1> element.

Expressions in JSX

JSX supports expression in pure JavaScript syntax. Expression has to be enclosed inside the curly braces, { }. Expression can contain all variables available in the context, where the JSX is defined.

Browser does not understand JSX directly. Because it's not valid JavaScript. So, to make it browser understandable there needs a compiler/transpiler which is called Babel. You can set up your own babel configuration or use vite or create-react-app which internally uses Babel for the JSX to JavaScript conversion.

Element is Deprecated #643.

That's why JSX was created to address clashes that might arise from the combination of HTML and JavaScript. One of those clashes is JavaScript's reserved keyword "class", and the class attribute of HTML. In this case, className becomes the JSX word for the class attribute of HTML.

JS is a programming language used for creating both frontend and backend applications. - JSX: It is a syntax extension for JavaScript, often used with React. JSX allows you to write HTML elements and components in a syntax that looks similar to XML or HTML.

What is JSX? JSX stands for JavaScript XML. JSX allows us to write HTML in React. JSX makes it easier to write and add HTML in React.

JSX (JavaScript XML) is a syntax extension for JavaScript that allows developers to write HTML-like code inside a JavaScript file. It was developed by Meta (formerly Facebook). The syntax of JSX resembles HTML, with opening and closing tags, attributes, and nested elements.

Sometimes, for readability, you might need to add comments to your code. Like most programming languages, JSX has its own way to do this. To put comments inside JSX, you use the syntax {/* */} to wrap around the comment text.

JSX is not a requirement for using React.

Using React without JSX is especially convenient when you don't want to set up compilation in your build environment.

How do I write code in React without JSX? ›

Yes, we can use react without jsx for that we need to use React. createElement() everywhere in code. So, anything you can do with JSX can also be done with just React. createElement() .

Upgrading to the new transform is completely optional, but it has a few benefits: With the new transform, you can use JSX without importing React. Depending on your setup, its compiled output may slightly improve the bundle size.

JSX as a barrier

ReactJS uses JSX. It's a syntax extension that allows HTML with JavaScript mixed together. This approach has its own benefits, but some members of the development community consider JSX as a barrier, especially for new developers. Developers complain about its complexity in the learning curve.

Simplifies the process of working with the DOM: JSX allows developers to write HTML-like elements directly in their JavaScript code, which makes it easier to create and manipulate the elements in the DOM. Improves readability and maintainability: JSX makes it easier to read and understand.

JSX performs optimization while compiling the source code to JavaScript. The generated code runs faster than an equivalent code written directly in JavaScript.

The dollar sign followed by curly braces ${} is used to evaluate and embed expressions dynamically in template literals. const name = 'John Doe'; const age = 20; // Using template literals for string interpolation console. log(`My name is ${name} and I'm ${age} years old.

Embedding JavaScript in JSX

JavaScript expressions may be embedded within JSX expressions. The embedded JavaScript expression must be wrapped in curly braces.

Therefore, JSX expressions are converted to strings and compiled into the JS equivalent. These features and behaviors result in a language that can improve development but is also very strict about syntax.