I'm using Windows 10 and I have a file called
pdf.html
pdf.html
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function goAndZoom(pageNum,zoom)
{
var pdf = document.getElementById('pdf');
pdf.data = pdf.data+'#page='+pageNum+'&zoom='+zoom;
document.body.removeChild(pdf);
document.body.appendChild(pdf);
}
</script>
</head>
<body>
<button onclick="goAndZoom(4,300);">Go to Page 4 and zoom 300%</button>
<object id="pdf" data="http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/pdf_open_parameters.pdf" width="100%" height="700px" type="application/pdf">
<param name="zoom" value="100" />
</object>
</body>
</html>
pdf.html
goAndZoom()