do - simple async JavaScript library

At the risk of having to change our name to Changelog.js as some have suggested, we feature another cool JavaScript library. Do from Tim Caswell who brought us the How To Node blog.

So what does Do do? First, it adds higher level processing for continuables, the callback pattern for asynchronous processing in Node.js.

As Tim explains:

A continuable is a function that returns a curried version of itself instead of a result directly. The last two arguments are the callback and the errback. So a continuable won’t execute until you attach callbacks to it:
function divide(a, b) { return function (callback, errback) {
  // the timeout it to prove that we're working asynchronously
  setTimeout(function () {
    if (b === 0) {
      errback(new Error("Cannot divide by 0"));
    } else {
      callback(a / b);
    }
  }); 
}}


divide(100, 10)(function (result) {
  puts("the result is " + result);
}, function (error) {
  throw error;
});

Building on continuables, Do adds two more important features.

Do.parallel

‘Do.parallel’ takes an array of actions and runs them in parallel

Do.parallel(
  Do.read("/etc/passwd"),
  Do.read(__filename)
)(function (passwd, self) {
  // Do something
}, error_handler);

Do.chain

Do.chain chains several actions together in the familiar jQuery style:

Do.chain(
  Do.read(__filename),
  function (text) { 
    return Do.save("newfile", text);
  },
  function () {
    return Do.stat("newfile");
  }
)(function (stat) {
  // Do something
}, error_handler);

Check out the README for full docs as well as other functions in Do.

[Source on GitHub]

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