Expressive, light-weight HTTP framework for node.js to make web applications and APIs more enjoyable to write. Koa requests flow through middleware in a stack-like manner, allowing you to perform actions downstream then filter and manipulate the response upstream. Koa's use of generators also greatly increases the readability and robustness of your application.
Only methods that are common to nearly all HTTP servers are integrated directly into Koa's small ~550 SLOC codebase. This includes things like content negotiation, normalization of node inconsistencies, redirection, and a few others.
Koa is not bundled with any middleware, but there is a large collection of community middleware to choose from.
$ npm install koa
Koa is supported in node v4+ and node v0.12 with the
Koa v2 is currently released with the
next tag (meaning it will not be marked as latest).
You can install it with semver:
npm install koa@2
In this new version, the middleware function signature changes to adopt async/await:
// Koa application is now a class and requires the new operator.const app = ;// uses async arrow functionsapp;app;
Until async/await is natively supported in Node Koa 1.x is the official release, however you may wish to adopt 2.x early by using Babel to compile. Koa 1.x generator-based middleware may be "upgraded" to the 2.x flavour using koa-convert.
var koa = ;var app = ;// loggerapp;// responseapp;app;
$ make test
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