JSFiddle - React, Tailwind, and code Playground

HTML

<form id="My50PageForm">
    
    <input name="forename" value="barny"> try editing this field<br>
    <input name="surname" value="something"><br>
    <button id="save">Check for changed values</button>
</form>

JavaScript

$(document).ready(function(){
    //Copy all form valued into a data attribute called 'original' when the page loads
    $("#My50PageForm :input").each(function(elem){
        $(this).data("original",$(this).val());
    });
    
    //here's where 
    $("#My50PageForm").submit(function(){        
        
        var elems = $("#My50PageForm :input").filter(function(value){
            var elem=$(this),
            original=elem.data("original");
            console.log(original);
            //check that original isn't 'undefined' (like the  button) and that it's been changed
            return original && elem.val()!==original
        });
        if(elems.length){
            $.post("http://jsfiddle.net/example.cfm",
                   elems.serialize());
        }else{
         alert("nothing changed");   
        }         
        
        return false;
    });
});