Use customCellValidatePost for custom behavior when focus leaves a cell, after the default Planning logic runs. This is similar to customCellValidatePre, which runs when the focus leaves a cell, after the Planning default logic if this function and the Planning default logic return True. If they return False, this function is disabled. Return values have no effect.
SampleValidateData.js includes an example for customCellValidatePre that you can use for this code. The example executes additional validation when the focus leaves a cell. The JavaScript code compares the value entered for the current year to the value for last year. If the current year value is over 10% larger than the previous year value, a message is displayed.