$watch an object

Call $watch with true as the third argument:

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

By default when comparing two complex objects in JavaScript, they will be checked for “reference” equality, which asks if the two objects refer to the same thing, rather than “value” equality, which checks if the values of all the properties of those objects are equal.

Per the Angular documentation, the third parameter is for objectEquality:

When objectEquality == true, inequality of the watchExpression is determined according to the angular.equals function. To save the value of the object for later comparison, the angular.copy function is used. This therefore means that watching complex objects will have adverse memory and performance implications.

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