KnockoutJS - Custom Observables

numericObservable

ko.numericObservable = function(initialValue) {
    var _actual = ko.observable(initialValue);
    var result = ko.dependentObservable({
        read: function() {
            return _actual();
        },
        write: function(newValue) {
            var parsedValue = parseFloat(newValue);
            _actual(isNaN(parsedValue) ? newValue : parsedValue);
        }
    });
    return result;
};

observableBoolean

ko.observableBoolean = function(initialValue) {
    var _actual = ko.observable(initialValue);
    var result = ko.dependentObservable({
        read: function() {
            return _actual();
        },
        write: function(initialValue) {
            switch(initialValue){
                case "0": case null: _actual(false); // Add false matches here
                default:  _actual(Boolean(initialValue));
            }
        }
    });
    return result;
};