ko.getUnusedFields(el)

ko.getUnusedFields.js

ko.getUnusedFields = function (el) {
    function isElement(obj) {
        try {
            //Using W3 DOM2 (works for FF, Opera and Chrom)
            return obj instanceof HTMLElement;
        }
        catch (e) {
            //Browsers not supporting W3 DOM2 don't have HTMLElement and
            //an exception is thrown and we end up here. Testing some
            //properties that all elements have. (works on IE7)
            return (typeof obj === "object") && (obj.nodeType === 1) && (typeof obj.style === "object") && (typeof obj.ownerDocument === "object");
        }
    }

    var vm = isElement(el) ? ko.dataFor(el) : el;

    var unusedFields = [];
    for (var fieldName in vm) {
        var field = vm[fieldName];
        if (field.getSubscriptionsCount && field.getSubscriptionsCount() == 0) {
            unusedFields.push(fieldName);
        }
    }
    return unusedFields;
};