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 completely changes in favor of ES2015-2016 syntax:
// Koa application is now a class and requires the new operator.const app = ;// uses async arrow functionsapp;app;
Although deprecated, the older, generator-based middleware signature will still work in v2 via koa-convert and will be removed in v3.
var koa = ;var app = ;// loggerapp;// responseapp;app;
$ make test
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