index.html

<!doctype html>
<html lang="en">
<head>
	<meta charset="utf-8"/>
	<script>
		function process(){
		let src = "process.php";
		src += "?path="+document.querySelector('#inputPath').value;
		document.querySelector('#myIframe').src=src;
		alert('allow little time to proces...');
		}
	
	</script>
	<style>
		html,body {font-family:Tahoma;background-color:#EEEEEE;}
	</style>
</head>
<body style="text-align:center">
	<br>
		<table style="width:100%">
			<tr>
					<td>Pdf path</td>
					<td> <input id="inputPath" name="path" value="D:/tempPdfs/italie magazine 2021_2_iPAD.pdf" style="width:90%" />  </td>
			</tr>
		</table>
	
	<br>
	Process PDF <a href="javascript:process()">here</a>
	<br><br>
	<iframe id='myIframe' style="height:calc(100vh - 200px);overflow:auto;border:1px solid #cccccc;width:90%;display:inline-block;background-color:white;"><iframe>

</body>
</html>