<div ng-app="app" ng-controller="test">
num:<input ng-model="num" />
<br/>
{{num | number}}
<br/>
{{num | number:2}}
<br/>
first name:<input ng-model="person.first"/>
<br/>
last name:<input ng-model="person.last"/>
<br/>
name: {{person | fullname}}
  <br/>
name: {{person | fullname:"- -"}}
    <br/>
name: {{person | fullname:" " | uppercase }}
</div>

function test($scope) {
}
angular.module("app", []).controller("test", test).
filter("fullname", function() {
  var filterfun = function(person, sep) {
    sep = sep || " ";
    person = person || {};
    person.first = person.first || "";
    person.last = person.last || "";
    return person.first + sep + person.last;
  };
  return filterfun;
});