D7net
Home
Console
Upload
information
Create File
Create Folder
About
Tools
:
/
opt
/
alt
/
alt-nodejs8
/
root
/
lib
/
node_modules
/
npm
/
node_modules.bundled
/
co
/
Filename :
Readme.md
back
Copy
# co [![Gitter][gitter-image]][gitter-url] [![NPM version][npm-image]][npm-url] [![Build status][travis-image]][travis-url] [![Test coverage][coveralls-image]][coveralls-url] [![Downloads][downloads-image]][downloads-url] 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](https://github.com/lukehoban/ecmascript-asyncawait). 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. ```js co(function* () { var result = yield Promise.resolve(true); return result; }).then(function (value) { console.log(value); }, function (err) { console.error(err.stack); }); ``` If you want to convert a `co`-generator-function into a regular function that returns a promise, you now use `co.wrap(fn*)`. ```js var fn = co.wrap(function* (val) { return yield Promise.resolve(val); }); fn(true).then(function (val) { }); ``` ## 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](https://github.com/TooTallNate/gnode) and/or [regenerator](http://facebook.github.io/regenerator/). io.js is supported out of the box, you can use `co` without flags or polyfills. ## Installation ``` $ npm install co ``` ## Associated libraries Any library that returns promises work well with `co`. - [mz](https://github.com/normalize/mz) - wrap all of node's code libraries as promises. View the [wiki](https://github.com/visionmedia/co/wiki) for more libraries. ## Examples ```js var co = require('co'); 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!](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) ### 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. ```js 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 `yieldable`s in parallel. ```js 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` 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. ```js 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`. ```js var fn = co.wrap(function* (val) { return yield Promise.resolve(val); }); fn(true).then(function (val) { }); ``` ## License MIT [npm-image]: https://img.shields.io/npm/v/co.svg?style=flat-square [npm-url]: https://npmjs.org/package/co [travis-image]: https://img.shields.io/travis/tj/co.svg?style=flat-square [travis-url]: https://travis-ci.org/tj/co [coveralls-image]: https://img.shields.io/coveralls/tj/co.svg?style=flat-square [coveralls-url]: https://coveralls.io/r/tj/co [downloads-image]: http://img.shields.io/npm/dm/co.svg?style=flat-square [downloads-url]: https://npmjs.org/package/co [gitter-image]: https://badges.gitter.im/Join%20Chat.svg [gitter-url]: https://gitter.im/tj/co?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge