Serially Iterating An Array, Asynchronously

serially-iterating-array.js

function run(steps, data, done) {
  // our recursion exit strategy:
  // no items left? we're done.
  if (steps.length === 0) {
    return done();
  }

  // get the first item in the array
  var step = steps.shift();

  // kick it off, here
  step(data, function(err) {
    if (err) { return done(err); }

    // process next items using recursion
    // keep in mind that steps.shift() removed the 1st fn from the array
    run(steps, data, done);
  });
}

An alternative to the example found here: http://derickbailey.com/2015/03/12/serially-iterating-an-array-asynchronously/

Hmm in fact Derick came up with the same solution in his library: https://github.com/derickbailey/migroose/blob/61b4510584fa222778b666ea997cdca34967cd5c/migroose/stepRunner/index.js#L17-L40

In the snippet above I'm not doing any wrapping of the step function in a setImmediate because I assume they're all async.