how to get value from js alert message to store in PHP varible?

[prohor]

I am trying to learn php and js. Here I am trying to put a value in php varible from javascript alert message input box but failed.
here what I have done so far,

// <?PHP and other variable is here....
$number='number'; 

<script>
			function number{
				
				if (fail == "") {
					number = prompt('Please enter Phone Number')
					if (number == "" || number == null) { 
						alert(' You have not specified the Phone Number. Please try again.'); 
						
						return false;
					}
					else {
						
						document.getElementById("number").value;
						
						return true;
					}
				}
				else { alert(fail); return false; }
			}
		</script>

So, actually how I can store the value from js alert to php varible? help me. Thanks for your valuable time and opinion.

[denno020]

The only way to get a value from JS to your PHP is to send a request from the JS to your server. This could either be through a form submission or an AJAX request

 

PHP is run on the server, whereas JS is run on the client, essentially 2 completely different places that each have no idea about the other.