Edit in JSFiddle

What's your name?:
<input type="text" focus ng-model="user.name" />
<button ng-click="greet()">Click here!</button>
<h3>{{ message }}</h3>
var app = angular.module('app', []);

app.controller('MainCtrl', function($scope) {
  $scope.greet = function() {
    $scope.message = "Hello, " + $scope.user.name;
  }
});

app.directive('focus', function() {
  return {
    link: function(scope, element, attrs) {
      element[0].focus();
    }
  };
});