> For the complete documentation index, see [llms.txt](https://simon-6.gitbook.io/simoncyber/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://simon-6.gitbook.io/simoncyber/portswigger-web-academy/xss/dom-based-xss/lab-3.md).
# Lab 3
#### The setup
Every HTML element has these properties. Say you have this on a page:
```html
Hello world
var el = document.getElementById('box');
```
`el.innerHTML` gives you (or sets) the HTML **inside** the element, not including the element itself.
```
el.innerHTML
// returns: "
Hello world
"
```
#### `outerHTML` — the element itself, contents *and* tags
`el.outerHTML` gives you (or sets) the HTML **of the element itself, including its opening and closing tags**.
**Reading:**
```javascript
el.outerHTML
// returns: '
Hello world
'
```
The `href` attribute is special. When a user clicks a link, the browser tries to navigate to whatever's in `href`. It supports several URL schemes:
* `http://...` → normal web request
* `https://...` → secure web request
* `mailto:...` → open email client
* `tel:...` → dial phone number
* `ftp://...` → FTP protocol
* **`javascript:...` → execute the rest as JavaScript**
When you look at:
```html
Sign in
```
You should see: "anchor tag, three attributes (href, class, onclick), content is 'Sign in'." This should be as automatic as reading English.
* Tags, Attributes, Content
**The complete list of void elements in HTML5:**
| Element | What it does |
| ---------- | --------------------------------------------- |
| `` | Clickable area in an image map |
| `` | Base URL for all relative URLs on the page |
| ` ` | Line break |
| `