Write to MySQL DB from HTML page

My goal is from a Bootstrap toggle button write on MySQL DB “yes” or “no”. I know that JavaScript in client-side so I found a way (but not sure is the best) to collect variable from JavaScript and pass it to a PHP file that will write on DB. My relevant code is below, but if I try, nothing happens. I suppose that inside my JavaScript code I have to call “function saveStato”, but I cannot understand in which way.

$(function() {
    $('.inServizio').change(function() {
        if($(this).prop('checked')){
        console.log('TEST_ON')
        function saveStato() {
            $.post("inServizio.php",
            {
            stato: $("SI").val(),
            },
        function(data,status){
            document.getElementById("saveWarningText").innerHTML = data;
            $( "#saveWarningText" ).fadeIn(100);
            setTimeout(function(){ $( "#saveWarningText" ).fadeOut(100); 
            }, 3000);
            });
        
        }
        } else {
            
               console.log('TEST_OFF')
         }

        //$(this).prop('checked')
    })
}); 

Answer

You can define it outside of your change listener, and call it inside with

saveStato();

Or just get rid of the function altogether and just have

$('.inServizio').change(function() {
    if($(this).prop('checked')){
        console.log('TEST_ON')
    
        $.post("inServizio.php",{stato: $("SI").val()},function(data,status){
            document.getElementById("saveWarningText").innerHTML = data;
            $( "#saveWarningText" ).fadeIn(100);
            setTimeout(function(){ $( "#saveWarningText" ).fadeOut(100); }, 3000);
        });
    
    } else { 
        //rest of your code
    }