My code:

```
<div id="main">
    <div id="div1">Keep this div</div>
    <div>1</div>
    <div>2</div>
    <div>3</div>
    <p>4</p>  
    <a href="">Keep this hyperlink</a>
</div>

<button id="button">Clear</button>

```

How can I remove everything after div with id div1 but keep the hyperlink when click the button which finally look like this:

```
<div id="main">
    <div id="div1">Keep this div</div>
    <a href="">Keep this hyperlink</a>
</div>

<button id="button">Clear</button> 

```