co-booster

co-booster is a performance tuning version of co. If you're already using co, you can make it work more faster by changing only the module. Naturally, It's fully compatible with co.

co is Generator based control flow goodness for nodejs and the browser, using promises, letting you write non-blocking code in a nice-ish way. You can check out co here.

This work is all thanks to tj who is the author of co.

How to change from co

Just change the module. You don't need anything else.

//var co = require('co');
var co = require('co-booster');

co(function *(){
  ...
});

Performance

• co() - benchmark code

  • Node 4.4.7 : 8% faster
  • Node 6.9.1 : 12% faster

• co.wrap() - benchmark code

  • Node 4.4.7 : 3% faster
  • Node 6.9.1 : 8% faster

• koa@1 style - benchmark code

  • Node 4.4.7 : 15% faster
  • Node 6.9.1 : 32% faster

Platform Compatibility

co-booster requires a Promise implementation. For versions of node < 0.11 and for many older browsers, you should/must include your own Promise polyfill.

When using node 0.10.x and lower or browsers without generator support, you must use gnode and/or regenerator.

When using node 0.11.x, you must use the --harmony-generators flag or just --harmony to get access to generators.

Node v4+ is supported out of the box, you can use co-booster without flags or polyfills.

Installation

$ npm install co-booster

Associated libraries

Any library that returns promises work well with co-booster.

• mz - wrap all of node's code libraries as promises.

View the wiki for more libraries.

Examples

var co = require('co-booster');

co(function *(){
  // yield any promise
  var result = yield Promise.resolve(true);
}).catch(onerror);

co(function *(){
  // resolve multiple promises in parallel
  var a = Promise.resolve(1);
  var b = Promise.resolve(2);
  var c = Promise.resolve(3);
  var res = yield [a, b, c];
  console.log(res);
  // => [1, 2, 3]
}).catch(onerror);

// errors can be try/catched
co(function *(){
  try {
    yield Promise.reject(new Error('boom'));
  } catch (err) {
    console.error(err.message); // "boom"
 }
}).catch(onerror);

function onerror(err) {
  // log any uncaught errors
  // co will not throw any errors you do not handle!!!
  // HANDLE ALL YOUR ERRORS!!!
  console.error(err.stack);
}

Yieldables

The yieldable objects currently supported are:

• promises
• thunks (functions)
• array (parallel execution)
• objects (parallel execution)
• generators (delegation)
• generator functions (delegation)

Nested yieldable objects are supported, meaning you can nest promises within objects within arrays, and so on!

Promises

Read more on promises!

Thunks

Thunks are functions that only have a single argument, a callback. Thunk support only remains for backwards compatibility and may be removed in future versions of co-booster.

Arrays

yielding an array will resolve all the yieldables in parallel.

co(function* () {
  var res = yield [
    Promise.resolve(1),
    Promise.resolve(2),
    Promise.resolve(3),
  ];
  console.log(res); // => [1, 2, 3]
}).catch(onerror);

Objects

Just like arrays, objects resolve all yieldables in parallel.

co(function* () {
  var res = yield {
    1: Promise.resolve(1),
    2: Promise.resolve(2),
  };
  console.log(res); // => { 1: 1, 2: 2 }
}).catch(onerror);

Generators and Generator Functions

Any generator or generator function you can pass into co-booster can be yielded as well. This should generally be avoided as we should be moving towards spec-compliant Promises instead.

How to skip errors in unsupported objects

If you set skipUnsupportError, co will no longer throw errors for unsupported objects.

co.skipUnsupportError = true;

co(function* () {
  yield undefined;
});

API

co(fn*).then( val => )

Returns a promise that resolves a generator, generator function, or any function that returns a generator.

co(function* () {
  return yield Promise.resolve(true);
}).then(function (val) {
  console.log(val);
}, function (err) {
  console.error(err.stack);
});

var fn = co.wrap(fn*)

Convert a generator into a regular function that returns a Promise.

var fn = co.wrap(function* (val) {
  return yield Promise.resolve(val);
});

fn(true).then(function (val) {

});

License

MIT