Check if an object has a property

This question already has an answer here:

Checking if a key exists in a JavaScript object? 16 answers

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You could use ' hasOwnProperty ' to check if object have the specific property.

if($scope.test.hasOwnProperty('bye')){
  // do this   
}else{
  // do this then
}

Here's a demo in jsFiddle.

Hope this helpful.

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if('bye' in $scope.test) {}
else {}

---

The problem is that you probably will have value not just when linking your directive - it could be loaded by $http for example.

My advice would be:

controller: function($scope) {
  $scope.$watch('test.hello', function(nv){ 
     if (!nv) return; 
     // nv has the value of test.hello. You can do whatever you want and this code
     // would be called each time value of 'hello' change
  });
}

or if you know that the value is assigned only one:

controller: function($scope) {
  var removeWatcher = $scope.$watch('test.hello', function(nv){ 
     if (!nv) return; 
     // nv has the value of test.hello. You can do whatever you want
     removeWatcher();
  });
}

This code will remove watcher the value of 'test.hello' was assigned (from any controller, ajax, etc etc)

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