Using prepopulated form, submit only changed fields

Question

I have an html form that uses select and text inputs. The form comes pre-populated with default values. How can I submit only the inputs that were changed by the user from the

Answer 1

As per Barmar's suggestion to use an array to track which values have changed, this is the solution I have come up with and it works.

Here is the js:

var tosubmit = []
function add(name) {
    if(tosubmit.indexOf(name) == -1)
        tosubmit.push(name);
}

function is_changed(name) {
    for(var k = 0; k < tosubmit.length; k++)
        if(name == tosubmit[k])
            return name && true;
    return false;
}

function before_submit() {
    var allInputs = document.getElementsByTagName("input");
    var allSelects = document.getElementsByTagName("select");
    for(var k = 0; k < allInputs.length; k++) {
        var name = allInputs[k].name;
        if(!is_changed(name))
            allInputs[k].disabled = true;
    }
    for(var k = 0; k < allSelects.length; k++) {
        var name = allSelects[k].name;
        if(!is_changed(name))
            allSelects[k].disabled = true;
    }
}

html:

    
    
    
        Option 1
        Option 2
    
    

This works because form elements that are disabled are not included in the POST Request. Thanks everyone for their suggestions.