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\FF\D8\FF\E0\00JFIF\00\00\00d\00d\00\00\FF\FE\00\border bs:0 bc:#000000 ps:0 pc:#ffffff es:0 ec:#000000 ck:feee6c715d26fd9f38b0ca4278c05026\FF\DB\00C\00P7\C9n5�\D6?\BD�\9Ds\EBp\9F[`8m\B7)o\B5\E8\E6I\99\FE3]]A2\BA\8Cw\D6E\93\\DEv\C8\009\F2\F1NI?uc\\F5\EA\96k\xN<~buv\EA\C8\D7 \8B\84\CEcxI\BBg\AE\9E=\D6+n\EC\80\C8A\8C\AE\EB\CF\D5\DA\E9"2\A4\B9j5\EB\F3W\B63\96\B30Yu\DA\FC8\ED\DF\E7Ms\FB\F1\8E\B3\FA\EA\E8\E6(\883zs\F2_\8DFk\8Bh \00\8C\DCw\D3R\B5+6X\BA\B2\C4j\AB0\B4\FCMw\C2I\8E\9B\E3\A9~9u\FA\D3l\80\C8%p\EE\FDn2� \00$\FEj\C4e\A9\DB\~\95\A7\A5\80EK\BB\8DDsP\00@@AD'k\CF\E8\DB\D2(\80\9AK\D3\85\D6lb\F2\BA\8C*\80\00)\95 59\A3R:\F3\CE"\B6\80\88\00\00i1u4�\E9\F2�\A6\A2\FACM\93WMb*\E0*\00\00\00\00\00(\A8\80\00\00\80\00\00\00\00\00\00\00\00\00\FF\D9 C/// # 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), Promi