Angular filter to change underscore values (- or _ seperated) to camelcase

angular.filters.u2camel.js

'use strict';

angular.module('app')
  .filter('u2camel', function($scope){
    return function(msg) {
      if (!angular.isString(msg)) {
        return '';
      } else {
        msg       = msg.replace(/(\_[a-z])/g, function($1){return $1.toUpperCase().replace('_','');});
        msg       = msg.replace(/(\-[a-z])/g, function($1){return $1.toUpperCase().replace('-','');});

        return msg;
      }
    };
  });