Negation in AngularJS expression. -

i have 1 noob question angularjs expressions. want check in expression (ngif in case) undefined. eg:

data-ng-if="typeof obj.property == 'undefined'"  

how can write expression check this? grateful ideas , recommendations.

best regards.

an undefined property falsy, don't have check unless care undefined. check be

data-ng-if="!user.email" 

that evaluate true unless user object had property email non-falsy value (0,'',undefined false). maybe after.