AngularJS replace filter

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope) {
  $scope.name = 'World';
});

app.filter('replace', [function () {

    return function (input, from, to) {
      
      if(input === undefined) {
        return;
      }
  
      var regex = new RegExp(from, 'g');
      return input.replace(regex, to);
       
    };


}]);

<!DOCTYPE html>
<html ng-app="plunker">

  <head>
    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="angular.js@1.0.x" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.0.8/angular.min.js" data-semver="1.0.8"></script>
    <script src="app.js"></script>
  </head>

  <body ng-controller="MainCtrl">
    <p>{{"I_am_the_coolest"|replace: '_':' '}}</p>
  </body>

</html>

/* Put your css in here */