AngularJS auto focus on another input when an input's text reach certain length

myModule.js

// The AngularJS code
var app = angular.module('autofocus', []);

app.directive('autofocusWhen', function () {
    return function (scope, element, attrs) {
        scope.$watch('maxLengthReach', function(newValue){
            if (newValue.length >= 5 ) {                                                   
                element[0].focus();
            }
        });
    }
});

ngAutoFocus.html

// The HTML code
<div ng-app="autofocus">
    <label>Name:</label>
    <input ng-model="maxLengthReach"></input>
    <br/><br/>
    <label>Title:</label>
    <input autofocus-when></input>
</div>