co
Generator based control flow goodness for nodejs and the browser, using promises, letting you write non-blocking code in a nice-ish way.
Co v4
co@4.0.0
has been released, which now relies on promises. It is a stepping stone towards ES7 async/await. The primary API change is how co()
is invoked. Before, co
returned a "thunk", which you then called with a callback and optional arguments. Now, co()
returns a promise.
If you want to convert a co
-generator-function into a regular function that returns a promise, you now use co.wrap(fn*)
.
Platform Compatibility
co@4+
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 0.11.x or greater, you must use the --harmony-generators
flag or just --harmony
to get access to generators.
When using node 0.10.x and lower or browsers without generator support, you must use gnode and/or regenerator.
io.js is supported out of the box, you can use co
without flags or polyfills.
Installation
Associated libraries
Any library that returns promises work well with co
.
mz - wrap all of node's code libraries as promises.
View the wiki for more libraries.
Examples
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
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
.
Arrays
yield
ing an array will resolve all the yieldables
in parallel.
Objects
Just like arrays, objects resolve all yieldable
s in parallel.
Generators and Generator Functions
Any generator or generator function you can pass into co
can be yielded as well. This should generally be avoided as we should be moving towards spec-compliant Promise
s instead.
API
co(fn*).then( val => )
Returns a promise that resolves a generator, generator function, or any function that returns a generator.
var fn = co.wrap(fn*)
Convert a generator into a regular function that returns a Promise
.
License
MIT
Last updated