如何在JavaScript的URL末尾添加变量值？

Question

I have a counter button which increases the number when clicked.
Also I have an URL like http://localhost:5000/x/ .

What I want is:
Printing the counter value at the end of the URL.

For example:
If counter=3,
I want to go http://localhost:5000/x/3 ;

My button type is submit and it increases the value of counter and goes the page http://localhost:5000/x/counter . However, I got 404 Error because the data is on the http://localhost:5000/x/3 . Here is the code.

<form action="http://localhost:5000/x/counter">

<script>
var add = (function () {
    var counter = 0;
    return function () {return counter += 1;}
})();

function myFunction(){
    document.getElementById("demo").innerHTML = add();
}
</script>

Thanks.Additional I don't use any framework and I want to handle it just by using JavaScript.

EDIT: Thanks for your answers. I solved it by using window.location.href function.

Answer 1

Retrieve counter using url of page

var counter = location.href.substring(location.href.lastIndexOf('/')+1);
counter = parseInt(counter);
counter += 1;

Set myform action using counter

document.myform.action = location.href.substring(0,location.href.lastIndexOf('/'))+counter;

Name your form

<form name='myform'>