!! THIS IS NOT A DUPLICATE !!
The question was not how to get an URL in Flask, but how to send data with jQuery to Flask!
I try to send and receive data with python, Flask and jQuery
The problem is that I want the full URL of the website and it is impossible to get it with flask because I make 'POST' requests. So with jQuery, I want to send the current URL.
I don't know how to send data (with jQuery) and receive data (with Flask).
Python/Flask code:
@app.route('/invisible', methods = ['POST'])
def dynamic_refresh():
    return jsonify({'somedata': 'data'})
HTML/jQuery code:
<script>
$(document).ready(function() {
    window.setInterval(function() {
        $.ajax({
            type : 'POST',
            url : '/invisible',
            //I tried to send data from here but it didn't worked
        })
        .done(function(data) {
            console.log(data)
            console.log(window.location.href)//the url I want to send
            //here I use the data received by the server
        })
    }, 5000);
});
</script>
 
    