JSFiddle - React, Tailwind, and code Playground

HTML

<form>
<input id="input1" name="input1" type="text" value="red" />
<input id="input1" name="input2" type="text" value="blue" />
</form>

JavaScript

var currentUlValues = {};
currentUlValues['input1'] = "red";
currentUlValues['input2'] = "blue";
needToConfirm = true;

$(window).on('beforeunload', function(){
    var is_return = false;
    if (needToConfirm) {
        $.each(currentUlValues, function(key, value) {
            var elem = $("#"+key).val();
            if (typeof elem !== 'undefined') {
                if (elem != currentUlValues[key]) {
                    is_return = true;
                    return false;
                }
            }
        });
        if (is_return) {
            return 'Are you sure you want to leave?';
        }
    }
});