npm i -g coden
npm i -g typings

git clone https://github.com/17koa/koa2-example.git
cd koa2-example
npm i
typings install
npm start

  "koa": "^2.0.0",
  "koa-bodyparser": "^2.0.1",
  "koa-convert": "^1.2.0",
  "koa-json": "^1.1.1",
  "koa-logger": "^1.3.0",
  "koa-onerror": "^1.2.1",
  "koa-router": "^7.0.0",
  "koa-static": "^1.5.2",
  "koa-views": "^5.0.1"

  "koa": "^2.0.0",
  "koa-router": "^7.0.0",
  "koa-views": "^5.0.1"

typings install node koa --ambient --save

/// <reference path="typings/main/ambient/node/index.d.ts"/>
/// <reference path="typings/main/ambient/koa/index.d.ts"/>