AngularJS - link in Custom Directive sample

AngularJS - link in Custom Directive sample

angular.module('b1').directive("extOnChanges", function ($translate) {
    return {
        restrict: 'A',
        link: function (scope, elem, attrs) {
            elem.on('click', function() {
                alert('You clicked me!');
                // elem.html('You clicked me');
            });
            elem.on('mouseenter', function() {
                elem.css('background-color', 'yellow');
            });
            elem.on('mouseleave', function() {
                elem.css('background-color', 'white');
            });
            elem.on('keydown', function(event) {
                if (event.keyCode === 13) {
                    alert('You entered me!');
                }
            });
        }
    }
});