Q:

Knockout databind on two variable

Is it possible to databind the enable property to two variables in KO?
<input type="checkbox" data-bind="enable: (prop1 || prop2), click: $root.rootProp />

A:

Yes, you absolutely can enable a checkbox based on two properties.
If this is your HTML:
<input type="checkbox" data-bind="enable: prop1() || prop2()" />

And this is your view model:
var viewModel = {
        prop1 : ko.observable(false),
        prop2 : ko.observable(true)
    };

ko.applyBindings(viewModel);

See this jsfiddle, and play around setting prop1 and prop2 to true or false.

