Comments in JSX

In JavaScript, you write comments with // or /* */, and in HTML with <!-- -->. Between the tags of JSX, neither works: <!-- is a mistake in the code (Identifier expected.), and // text is ordinary text, which shows on the page.

A comment in JSX is a JavaScript comment in curly braces:

<main>
    {/* The organizers send the lineup on Monday. */}
    <h1>Summer Sounds</h1>
</main>

The braces say "here comes JavaScript", and in them is only a comment, which JavaScript skips. Above return, outside JSX, you write comments as you always have, with //.

Comments are also handy for hiding part of the page for a while, without deleting it: put the elements between {/* and */}, and they're gone from the page until you remove the comment again.