react.dev/docs/02.3-jsx-gotchas.md

---
id: jsx-gotchas
title: JSX Gotchas
permalink: jsx-gotchas.html
prev: jsx-spread.html
next: interactivity-and-dynamic-uis.html
---

JSX looks like HTML but there are some important differences you may run into.

> Note:
>
> For DOM differences, such as the inline `style` attribute, check [here](/react/docs/dom-differences.html).

## HTML Entities

You can insert HTML entities within literal text in JSX:

```javascript
<div>First &middot; Second</div>
```

If you want to display an HTML entity within dynamic content, you will run into double escaping issues as React escapes all the strings you are displaying in order to prevent a wide range of XSS attacks by default.

```javascript
// Bad: It displays "First &middot; Second"
<div>{'First &middot; Second'}</div>
```

There are various ways to work-around this issue. The easiest one is to write Unicode characters directly in JavaScript. You need to make sure that the file is saved as UTF-8 and that the proper UTF-8 directives are set so the browser will display it correctly.

```javascript
<div>{'First · Second'}</div>
```

A safer alternative is to find the [unicode number corresponding to the entity](http://www.fileformat.info/info/unicode/char/b7/index.htm) and use it inside of a JavaScript string.

```javascript
<div>{'First \u00b7 Second'}</div>
<div>{'First ' + String.fromCharCode(183) + ' Second'}</div>
```

You can use mixed arrays with strings and JSX elements. Each JSX element in the array needs a unique key.

```javascript
<div>{['First ', <span key="middot">&middot;</span>, ' Second']}</div>
```

As a last resort, you always have the ability to [insert raw HTML](/react/tips/dangerously-set-inner-html.html).

```javascript
<div dangerouslySetInnerHTML={{'{{'}}__html: 'First &middot; Second'}} />
```


## Custom HTML Attributes

If you pass properties to native HTML elements that do not exist in the HTML specification, React will not render them. If you want to use a custom attribute, you should prefix it with `data-`.

```javascript
<div data-custom-attribute="foo" />
```

However, arbitrary attributes are supported on custom elements (those with a hyphen in the tag name or an `is="..."` attribute).

```javascript
<x-my-component custom-attribute="foo" />
```

[Web Accessibility](http://www.w3.org/WAI/intro/aria) attributes starting with `aria-` will be rendered properly.

```javascript
<div aria-hidden={true} />
```