This is an AngularJS filter to linkify #hashtags and @mention texts into respective Twitter URLsDemo - http://plnkr.co/edit/vrdgxU?p=preview

new.js

    app.filter('hashtags',['$filter', '$sce', 
        function($filter, $sce) {
            return function(text, target, type) {
            if (!text) return text;
        var replacedText = $filter('linky')(text, target);
        var targetAttr = "";
        if (angular.isDefined(target)) {
            targetAttr = ' target="' + target + '"';
        }
        if(type === 'twitter'){
            // replace #hashtags and send them to twitter
            var replacePattern1 = /(^|\s)#(\w*[a-zA-Z_]+\w*)/gim;
            replacedText = text.replace(replacePattern1, '$1<a class="hashtag" href="https://twitter.com/search?q=%23$2"' + targetAttr + '>#$2</a>');
            // replace @mentions but keep them to our site
            var replacePattern2 = /(^|\s)\@(\w*[a-zA-Z_]+\w*)/gim;
            replacedText = replacedText.replace(replacePattern2, '$1<a class="hashtag" href="https://twitter.com/$2"' + targetAttr + '>@$2</a>');
        } else if(type === 'facebook'){
            // replace #hashtags and send them to facebook
            var replacePattern1 = /(^|\s)#(\w*[a-zA-Z_]+\w*)/gim;
            replacedText = text.replace(replacePattern1, '$1<a class="hashtag" href="https://facebook.com/hashtag/$2"' + targetAttr + '>#$2</a>');
        }


        $sce.trustAsHtml(replacedText);
        return replacedText;
    };
}

tweetLinky.js

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

app.filter('tweetLinky',['$filter', '$sce',
  function($filter, $sce) {
    return function(text, target) {
      if (!text) return text;

      var replacedText = $filter('linky')(text, target);
      var targetAttr = "";
      if (angular.isDefined(target)) {
          targetAttr = ' target="' + target + '"';
      }

      // replace #hashtags
      var replacePattern1 = /(^|\s)#(\w*[a-zA-Z_]+\w*)/gim;
      replacedText = replacedText.replace(replacePattern1, '$1<a href="https://twitter.com/search?q=%23$2"' + targetAttr + '>#$2</a>');

      // replace @mentions
      var replacePattern2 = /(^|\s)\@(\w*[a-zA-Z_]+\w*)/gim;
      replacedText = replacedText.replace(replacePattern2, '$1<a href="https://twitter.com/$2"' + targetAttr + '>@$2</a>');

      $sce.trustAsHtml(replacedText);
      return replacedText;
    };
  }
]);