Watching multiple values all at once in angularjs

We know how to watch a variable on the scope.

$scope.$watch('var1',function(newVal,oldVal){
 console.log(newVal);
  });

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Say if we want to watch three variables inside our controller we have to have three watch blocks as shown

$scope.$watch('var1',function(newVal,oldVal){
 console.log(newVal);
  });

  $scope.$watch('var2',function(newVal,oldVal){
 console.log(newVal);
  });

  $scope.$watch('var3',function(newVal,oldVal){
 console.log(newVal);
  });

This will increase your number of lines of code and may become hard to manage if you have number of watch blocks.
Angular introduced $watchGroup in version 1.3 using which we can watch multiple variables, with a single $watchGroup block
$watchGroup takes array as first parameter in which we can include all of our variables to watch.

$scope.$watchGroup(['var1','var2','var3'],function(newVals,oldVals){
   console.log(newVals);
 });