Making an ajax request on next

[debuGhy]

I want to know how to save the data of every step individually. I want to save every step's form data separately for which I want to make an ajax request.

[debuGhy]

Checking the active index I managed calling the api by using this--

$(document).on("msf:viewChanged", function(event, data){
        API call
});

Suppose If API has some error how to stop the current step to go next? Can you help?