angular Creating a Directive that Adds Event Listeners

<span my-draggable>Drag ME</span>

angular.module('dragModule', [])
.directive('myDraggable', ['$document', function($document) {
return {
link: function(scope, element, attr) {
var startX = 0, startY = 0, x = 0, y = 0;

element.css({
position: 'relative',
border: '1px solid red',
backgroundColor: 'lightgrey',
cursor: 'pointer'
});

element.on('mousedown', function(event) {
// Prevent default dragging of selected content
event.preventDefault();
startX = event.pageX - x;
startY = event.pageY - y;
$document.on('mousemove', mousemove);
$document.on('mouseup', mouseup);
});

function mousemove(event) {
y = event.pageY - startY;
x = event.pageX - startX;
element.css({
top: y + 'px',
left:  x + 'px'
});
}

function mouseup() {
$document.off('mousemove', mousemove);
$document.off('mouseup', mouseup);
}
}
};
}]);