koajs/examples

★ 4,536JavaScriptAudience · developerComplexity · 1/5Setup · easy

Mindmap

mindmap
  root((koajs examples))
    Core Examples
      Cookie handling
      File uploads
      Error handling
    Middleware Patterns
      CSRF protection
      Virtual hosts
      Conditional logic
    External Starters
      MongoDB blog
      React to-do app
      TypeScript starters
    Purpose
      Learning resource
      Copy-paste reference
      Minimal code demos

mindmap root((koajs examples)) Core Examples Cookie handling File uploads Error handling Middleware Patterns CSRF protection Virtual hosts Conditional logic External Starters MongoDB blog React to-do app TypeScript starters Purpose Learning resource Copy-paste reference Minimal code demos

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Things people build with this

USE CASE 1

Learn how to implement CSRF protection in a Koa app by reading and running the included example

USE CASE 2

Set up file upload handling in Node.js using the Koa multipart upload example as a starting point

USE CASE 3

Build a multi-tenant server that serves different content by domain name using the virtual hosts example

USE CASE 4

Scaffold a Koa app with MongoDB, authentication, or TypeScript using the linked external starter repos

Tech stack

JavaScriptNode.jsKoa

Getting it running

Difficulty · easy Time to first run · 5min

In plain English

Koa is a web framework for Node.js, built by the same team that created Express. It uses a different approach to handling requests: middleware functions are written as async functions and run in a predictable order using a concept sometimes called the "onion" model. This repository is a companion collection of small, self-contained example applications that show how to use Koa for common server-side tasks. The bundled examples cover a wide range of typical web development needs: handling 404 errors, parsing request bodies, managing cookies, protecting forms with CSRF tokens, rendering HTML templates, streaming files, handling file uploads, running middleware conditionally, and setting up virtual hosts that serve different content depending on the domain name. Each example lives in its own folder and is meant to be read and run independently, so you can focus on exactly the pattern you need. Beyond the bundled examples, the README lists a number of external repositories that demonstrate Koa in more complete applications. These include a blog backed by MongoDB, a REST API skeleton, a to-do app that pairs Koa with React, and several starter kits that add TypeScript, user authentication with Passport, database access via Postgres or Mongoose, and Docker support. There are also links to Yeoman generators for scaffolding Koa projects, boilerplates for API development and microservices, and a couple of tutorial articles on building REST APIs and adding user login flows. This repository is primarily a learning resource rather than a deployable application. If you are trying to understand how Koa works or how to wire up a specific feature such as flash messages, content negotiation, or server-sent events, the examples here show the minimal amount of code needed to make that feature run. The README does not explain Koa in depth, it assumes you will open the example folders and read the source files directly.

Copy-paste prompts

Prompt 1

Using the Koa examples repo as a reference, show me how to set up multipart file upload handling in a Koa app and save uploaded files to a local folder.

Prompt 2

I want to add CSRF token protection to my Koa app. Walk me through the middleware setup based on the pattern in the koajs/examples collection.

Prompt 3

How do I implement virtual hosts in Koa so that api.example.com and www.example.com are handled by completely different middleware stacks?

Prompt 4

Show me how to stream a large file as a download response in Koa using the streaming example pattern from koajs/examples.

Prompt 5

I'm migrating an Express app to Koa. Using the koa examples as reference, explain how the onion middleware model differs from Express middleware and how to rewrite my existing middleware functions.

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