async template loading with requests caching

async-template.js

/**
 * Asynchronously fetches a template & caches it internally
 * 
 * If a request for a template hasn't completed yet and another
 * request arrives, then instead of queuing the request resolve
 * the deffered with the previously cached request
 */
function fetchTemplate(path) {
  
  /**
   * Template Cache
   * 
   * Stores the actual template content
   */
  var JST = Backbone.Layout.cache('template-cache');
  
  /**
   * Template Request Cache
   * 
   * Keeps a tab on ongoing requests
   */
  var reqcache = Backbone.Layout.cache('template-req-queue');

  // return the template content if already in cache
  if (JST[path]) {
    return JST[path];
  }

  // make this function async
  var done = this.async();

  if (!reqcache[path]) {
    // if this is a new request then
    // do the request
    var req = $.get(path, null, null, 'text');
    
    // and add in request cache
    reqcache[path] = req;
    
    // run a function request completes
    req.done(complete);
  } else {
    // if we have already seen this request
    // then wait for the ongoing request to
    // complete and resolve the latter requests
    // with former's response
    reqcache[path].done(complete);
  }

  function complete(contents) {
    // compile the template & cache it
    done(JST[path] = _.template(contents));

    if (path in reqcache){ 
      delete reqcache[path];
    }
  }

}