I wanted to use a bunch of underscore.string (http://epeli.github.io/underscore.string/) functions as filters in an AngularJS project and rather than writing separate filters for each function I came up with this.

gistfile1.js

/** 
 *  call titleize like:
 *    {{ expression | _str.'titleize' }}
 *  call truncate like:
 *    {{ expression | _str:'truncate':5:'...' }}
 *  etc.
 */
app.filter('_str', function() {
  return function(text, fn) {
    var args = Array.prototype.slice.call(arguments, 2);
    args.unshift(text);

    return _.str[fn].apply(fn, args);
  };
});