Refreshing Oauth2 Tokens In Async Js

I have a single page app that talks to an API. I own both parts (the API and the single page app aka 'official client'). The client is javascript, so asynchronous. The problem I ha

Solution 1:

Found out myself, this works for me (CoffeeScript, Object.clone is from Sugar.JS):

  tokenReloadPromise = null

  $.ajaxPrefilter (options, userOptions, xhr)=>
      if tokenReloadPromise?
        xhr.abort()
        tokenReloadPromise.then ->
          options.noTokenRefresh = true
          $.ajax(options)
      else
        originalOptions = Object.clone(options)
        # configure access token for request here
        unless options.noTokenRefresh == true
          options.error = (xhr)->
            if xhr.status == 401
              tokenReloadPromise ?= new jQuery.Deferred
              tokenReloadPromise.then ->
                originalOptions.noTokenRefresh = true
                $.ajax(originalOptions)
              App.execute "refresh:access_token", ->
                promise = tokenReloadPromise
                tokenReloadPromise = null
                promise.resolve()
            else
              originalOptions.error.apply(this, arguments)
    true