Watching Attribute Value with $observe

Below is an example of how to watch for an attribute's value and do something every time it has changed. To do this we would use $observe function.

<!-- origin markup in the view -->
enter a colour: <input class="observe-test" data-ng-model="inputValue" title="{{inputValue}}"/> 
<br />
value typed: <span></span>

// directive codes
myApp.directive('observeTest', function () {
    return {
        restrict: 'C',
        link: function (scope, element, attrs) {
            attrs.$observe('title', function (newValue) {
              attrs.$set('style', 'color:' + newValue);
              element.parent().find('span').text(newValue);
            })
        }
    }
});

See the example in Plunker