asyncWithRetry

gistfile1.js

// Takes an asynchronous function func and returns an asynchronous function decoratedFunc that
// calls func until it either runs out of tries or doesn't pass an error into the callback
// makes numRetries available as the last argument in func
var asyncWithRetry = function (func, numRetries) {
  var decoratedFunc = function () {
    var currentRetry, args, callback, newCallback, callbackArgs, err;

    currentRetry = 0;

    args = Array.prototype.slice.call(arguments, 0);

    // Replace the callback with one that has retry logic
    callback = args[args.length - 1];
    newCallback = function () {
      currentRetry += 1;

      callbackArgs = Array.prototype.slice.call(arguments, 0);
      err = callbackArgs[0];

      if (err && currentRetry < numRetries) {
        args.splice(args.length - 1, 1, currentRetry);
        func.apply(null, args);
      } else {
        callback.apply(null, callbackArgs);
      }
    };
    args.splice(args.length - 1, 1, newCallback, currentRetry);

    func.apply(null, args);
  };

  return decoratedFunc;
};