data de formato com moment.js

Eu tenho uma string neste formato:

var testDate = Fri Apr 12 2013 19:08:55 GMT-0500 (CDT)

Eu gostaria de usar moment.js obtê-lo neste formatomm/dd/yyyy : 04/12/2013 para exibição.

Eu tentei fazer isso usando esse método,

moment(testDate,'mm/dd/yyyy');

Quais erros e dizthere is no such method called replace ? Estou me aproximando disso da maneira errada?

Editar:

Também devo mencionar que estou usando uma versão pré-empacotada do moment.js, empacotada para o mete.j.j

Object [object Date] has no method 'replace' : The Exact error from the console

Rastreamento de pilha:

 at makeDateFromStringAndFormat (http://127.0.0.1:3000/packages/moment/lib/moment/moment.js?b4e3ac4a3d0794023a4410e7941c3e179398b5b0:539:29)
    at moment (http://127.0.0.1:3000/packages/moment/lib/moment/moment.js?b4e3ac4a3d0794023a4410e7941c3e179398b5b0:652:24)
    at populateProfileForEdit (http://127.0.0.1:3000/client/views/home/administration/directory/profiles/profiles.js?acfff908a6a099f37312f62892a22b40f82e5e0f:147:25)
    at Object.Template.profile_personal.rendered (http://127.0.0.1:3000/client/views/home/administration/directory/profiles/profiles.js?acfff908a6a099f37312f62892a22b40f82e5e0f:130:13)
    at Spark.createLandmark.rendered (http://127.0.0.1:3000/packages/templating/deftemplate.js?b622653d121262e50a80be772bf5b1e55ab33881:126:42)
    at http://127.0.0.1:3000/packages/spark/spark.js?45c746f38023ceb80745f4b4280457e15f058bbc:384:32
    at Array.forEach (native)
    at Function._.each._.forEach (http://127.0.0.1:3000/packages/underscore/underscore.js?867d3653d53e9c7a171483edbcad9670e12288c7:79:11)
    at http://127.0.0.1:3000/packages/spark/spark.js?45c746f38023ceb80745f4b4280457e15f058bbc:382:7
    at _.extend.flush (http://127.0.0.1:3000/packages/deps/deps.js?9642a93ae1f8ffa8eb1c2475b198c764f183d693:231:11) 

questionAnswers(2)

yourAnswerToTheQuestion