Overview

Yaku is full compatible with ES6's native Promise, but much faster, and more error friendly. If you want to learn how Promise works, read the minimum implementation yaku.aplus. Without comments, it is only 80 lines of code (gzipped size is KB). It only implements the constructor and then.

Yaku passed all the tests of promises-aplus-tests, promises-es6-tests, and even the core-js tests.

I am not an optimization freak, I try to keep the source code readable and maintainable. I write this lib to research one of my data structure ideas: docs/lazyTree.md.

Features

• One of the best for mobile, gzipped file is only 1.9KB
• Supports "uncaught rejection" and "long stack trace", Comparison
• Works on IE5+ and other major browsers
• 100% statement and branch test coverage
• Better CPU and memory performance than the native Promise
• Well commented source code with every Promises/A+ spec
• Highly modularized extra helpers, no pollution to its pure ES6 implements
• Supports ES7 finally

Quick Start

Node.js

npm install yaku

Then:

var Promise = require('yaku');

Or if you don't want any extra debug helper, ES6 only version is here:

var Promise = require('yaku/lib/yaku.core');

Or if you only want aplus support:

var Promise = require('yaku/lib/yaku.aplus');

Browser

Raw usage:

<script type="text/javascript" src="https://raw.githubusercontent.com/ysmood/yaku/master/src/yaku.js"></script>
<script>
    // Yaku will be assigned to `window.Yaku`.
    var Promise = Yaku;
</script>

Change Log

docs/changelog.md

Compare to Other Promise Libs

These comparisons only reflect some limited truth, no one is better than all others on all aspects. There are tons of Promises/A+ implementations, you can see them here. Only some of the famous ones were tested.

Date: Sat Dec 17 2016 22:15:40 GMT+0800 (CST)
Node v7.2.1
OS   darwin
Arch x64
CPU  Intel(R) Core(TM) i7-4850HQ CPU @ 2.30GHz

| name | unit tests | coverage | 1ms async task | optional helpers | helpers | gzip | | ---- | ---------- | -------- | -------------- | ---------------- | ------- | ---- | | yaku@0.17.4 | ✓ | 100% 100% | 221ms / 108MB | ✓ | 34 | 1.9KB | | yaku.core@0.17.4 | ✓ | 100% 100% | 217ms / 108MB | ✓ | 28 | 1.6KB | | yaku.aplus@0.17.4 | x (90 failed) | 100% 100% | 262ms / 116MB | ✓ | 7 | 0.5KB | | bluebird@3.4.6 | x (34 failed) | 99% 96% | 207ms / 81MB | partial | 102 | 15.9KB | | es6-promise@4.0.5 | x (52 failed) | ? ? | 432ms / 114MB | x | 12 | 2.4KB | | pinkie@2.0.4 | x (44 failed) | ? ? | 313ms / 135MB | ✓ | 10 | 1.2KB | | native@7.2.1 | ✓ | ? ? | 376ms / 134MB | x | 10 | 0KB | | core-js@2.4.1 | x (9 failed) | ? ? | 394ms / 142MB | x | 10 | 5KB | | es6-shim@0.35.2 | ✓ | ? ? | 390ms / 136MB | x | 10 | 15.5KB | | q@1.4.1 | x (42 failed) | ? ? | 1432ms / 370MB | x | 74 | 4.6KB | | my-promise@1.1.0 | x (10 failed) | ? ? | 786ms / 232MB | x | 10 | 3.9KB |

• unit test: promises-aplus-tests, promises-es6-tests, and even the core-js tests.

• coverage: statement coverage and branch coverage.

• helpers: extra methods that help with your promise programming, such as async flow control helpers, debug helpers. For more details: docs/debugHelperComparison.md.

• 1ms async task: npm run no -- benchmark, the smaller the better (total time / memory rss).

• promises-es6-tests: If you want to test bluebird against promises-es6-tests, run npm run no -- test-es6 --shim bluebird.

• optional helpers: Whether the helpers can be imported separately or not, which means you can load the lib without helpers. Such as the bluebird-core, it will inevitably load some nonstandard helpers: spread, promisify, etc.

FAQ

• catch on old browsers (IE7, IE8 etc)?

  In ECMA-262 spec, catch cannot be used as method name. You have to alias the method name or use something like Promise.resolve()['catch'](function() {}) or Promise.resolve().then(null, function() {}).

• When using with Babel and Regenerator, the unhandled rejection doesn't work.

  Because Regenerator use global Promise directly and don't have an api to set the Promise lib. You have to import Yaku globally to make it use Yaku: require("yaku/lib/global");.

Unhandled Rejection

Yaku will report any unhandled rejection via console.error by default, in case you forget to write catch. You can catch them manually:

• Browser: window.onunhandledrejection = ({ promise, reason }) => { /* Your Code */ };
• Node: process.on("unhandledRejection", (reason, promise) => { /* Your Code */ });

For more spec read Unhandled Rejection Tracking Browser Events.

API

• require('yaku')

• require('yaku/lib/utils') or any of them like require('yaku/lib/retry')

• require('yaku/lib/Observable')

Utils

It's a bundle of all the following functions. You can require them all with var yutils = require("yaku/lib/utils"), or require them separately like require("yaku/lib/flow"). If you want to use it in the browser, you have to use browserify or webpack. You can even use another Promise lib, such as:

require("yaku/lib/_").Promise = require("bluebird");
var source = require("yaku/lib/source");

// now "source" use bluebird instead of yaku.

Observable

Unit Test

This project use promises-aplus-tests to test the compliance of Promises/A+ specification. There are about 900 test cases.

Use npm run no -- test to run the unit test against yaku.

Test other libs

basic test

To test bluebird: npm run no -- test-basic --shim bluebird

The bluebird can be replaced with other lib, see the test/getPromise.js for which libs are supported.

aplus test

To test bluebird: npm run no -- test-aplus --shim bluebird

The bluebird can be replaced with other lib, see the test/getPromise.js for which libs are supported.

es6 test

To test bluebird: npm run no -- test-es6 --shim bluebird

The bluebird can be replaced with other lib, see the test/getPromise.js for which libs are supported.

Benchmark

Use npm run no -- benchmark to run the benchmark.

async/await generator wrapper

Node v5.6.0
OS   darwin
Arch x64
CPU  Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz

yaku: 117ms
co: 283ms
bluebird: 643ms

Contribution

Make sure you have npm and npm install at the root of the project first.

Other than use gulp, all my projects use nokit to deal with automation. Run npm run no -- -h to print all the tasks that you can use.

Update readme.md

Please don't alter the readme.md directly, it is compiled from the docs/readme.jst.md. Edit the docs/readme.jst.md and execute npm run no to rebuild the project.