Select text in element

I have an input element and it has text inside it by using ng-model, then I'm trying to select all text by creating custom detective:

.directive('selectText', function() {
    return {
        require: 'ngModel',
        link: function(scope, elem, attrs, ctrl) {
            elem.bind('focus', function() {
                $(elem).select();
            });
            scope.$watch("edit",function(newValue,oldValue) {
                $(elem).select();
            });
        }
    };
})

It works well, but I don't want it's text to be also selected when user foucusout from the control and focusin again. It should just select text only once (not on second focus). Also how can I remove focus from element when all text is selected?