Building something like this?
Wondering where to get this "-" state in checkbox?
Well, its very easy in HTML5.
You can access an property of an input field object called Indeterminate
Its a Boolean property, true will display "-" in checkbox; false, wont do anything.
Note: you cannot use it as an attribute in input field
Just to remember, all the input field has Indeterminate state but it only acts on checkboxes.