butler

Node Butler

This module helps when you need to call several asynchronous calls one after each other.

Install

npm install butler

Example

// fs.readFile() implementation (check examples/fs.js)
var fs = require("fs"),
    Butler = require("./../lib/butler").Butler,
    Alfred = new Butler();

// fs.readFile()
function readFileAsync(filename, cb) {
  Alfred
    .add(fs.open, filename, "r")
    .store("fd") // store return value from previous call as 'fd'
    .add(fs.fstat)
    .wait(function (err) {
      if (err) { cb(err); return false; }

      var size = this.params.get(0).size;
      this.params.set(this.storage.fd, new Buffer(size), 0, size, 0); // remember 'fd' ?
    })
    .add(fs.read)
    .wait(function (err) {
      if (err) { cb(err); return false; }

      this.storage.data = this.params.get(1);
      this.params.set(this.storage.fd);
    })
    .add(fs.close)
    .wait(function (err) {
      if (err) { cb(err); return false; }
      cb(null, this.storage.data);
    });
}

readFileAsync(__dirname + "/fs.js", function (err, data) {
  if (err) {
    return console.log("error reading file", err);
  }
  console.log("FILE\n-------------------------");
  console.log(data);
  console.log("-------------------------");
});