Previous value of the checkbox

How can i know the provious state of the a checkbox in a grid before edit?



mygrid1.attachEvent(“onCheckbox”,function(id,ind,state)

{



});

The event occurs only when checkbox state changed.
If “state” has true value => checkbox was unchecked and switched to checked state now
If “state” has false value => checkbox was checked and switched to unchecked state now