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.

Coding JSX

• JSX allows us to write HTML elements in JavaScript and place them in the DOM without any createElement() and/or appendChild() methods.
• JSX converts HTML tags into react elements.

You are not required to use JSX, but JSX makes it easier to write React applications.

Expressions in JSX

With JSX you can write expressions inside curly braces { }.

The expression can be a React variable, or property, or any other valid JavaScript expression. JSX will execute the expression and return the result.

Inserting a Large Block of HTML

To write HTML on multiple lines, put the HTML inside parentheses.

One Top Level Element

The HTML code must be wrapped in ONE top level element.

So if you like to write two paragraphs, you must put them inside a parent element, like a div element.

JSX will throw an error if the HTML is not correct, or if the HTML misses a parent element.

Alternatively, you can use a fragment to wrap multiple lines. This will prevent unnecessarily adding extra nodes to the DOM.

A fragment looks like an empty HTML tag: <></>.

Elements Must be Closed

JSX follows XML rules, and therefore HTML elements must be properly closed.

JSX will throw an error if the HTML is not properly closed.

Attribute class = className

The class attribute is a much used attribute in HTML, but since JSX is rendered as JavaScript, and the class keyword is a reserved word in JavaScript, you are not allowed to use it in JSX.

Use attribute className instead.

JSX solved this by using className instead. When JSX is rendered, it translates className attributes into class attributes.

Conditions - if statements

React supports if statements, but not inside JSX.

To be able to use conditional statements in JSX, you should put the if statements outside of the JSX, or you could use a ternary expression instead.