NodeJS Async Waterwall

nodejs-async-waterfall-example.js

function foo(arg, callback) {
  if (arg < 0) {
    callback('error');
    return;
  }
  callback(null, arg+1);
}

function bar(arg, callback) {
  if (arg < 0) {
    callback('error');
    return;
  }
  callback(null, arg+2);
}

function baz(arg, callback) {
  if (arg < 0) {
    callback('error');
    return;
  }
  callback(null, arg+3);
}

async.waterfall([
  (cb) => {
    foo(0, cb);
  },
  (arg, cb) => {
    bar(arg, cb);
  },
  (arg, cb) => {
    baz(arg, cb);
  }
], (err, result) => {
  if (err) {
    console.log(err);
  } else {
    console.log(result); //6
  }
});