whenClient checkbox not working in yii2?

Question

JavaScript

There is a checkbox on the form , but this line does not work [['login','district'],'unique', 'whenClient'=>"function (attribute,value) { return !($(#TV).prop( 'checked'))}"]. Though similar line with dropdownList works fine

Answer 1

I think I missed quotes:

function (attribute,value) {
  return $('#TV').not(':checked');
}

Answer 2

I still don't understand why it doesn't work. Wrote ajax validation