step-3.md

Step 3 - Add Typescript support

Next, you're going to add Typescript to the project. Typescript is a typed superset of JavaScript that brings several advantages including:

• Static Type-checking
• ES6 feature support
• Advanced editor features, like autocomplete

Install and configure typescript

npm install -g typescript@next
npm install --save-dev typescript@next

Installing globally provides access to the typescript cli. Installing in the project ensures we track Typescript as a dependency and makes it available for CI servers.

Create a tsconfig.json file in the project root and include the following:

{
  "compilerOptions": {
    "target": "es6",
    "rootDir": ".",
    "module": "commonjs",
    "moduleResolution": "node",
    "noImplicitAny": true,
    "removeComments": true,
    "inlineSourceMap": true,
    "inlineSources": true,
    "pretty": true
  },
  "filesGlob": [
    "functions/**/*.ts"
  ],
  "include": [
    "functions/**/*.ts"
  ]
}

Install and configure typings

Typings is a tool to install and manage TypeScript definitions.

npm install --save-dev typings

Next, install the TypeScript defintions for Node.js 4.

typings install --save --global dt~node-4

Add "typings/index.d.ts" to the filesGlob and include arrays in your tsconfig.json. They should look like this:

"filesGlob": [
  "functions/**/*.ts",
  "typings/index.d.ts"
],
"include": [
  "functions/**/*.ts",
  "typings/index.d.ts"
]

This what your tsconfig.json file should look like.

Migrate function to typescript

Rename handler.js in your urlToMd directory to handler.ts. As Typescript is a superset of JavaScript, you can immediately compile handler.ts to JavaScript (albeit with a few errors.) Try running tsc from your project root to compile.