step-7.md

Step 7 - Write the Lambda function part 2 - upndown

You'll be using the upndown library to convert the simplified HTML from readability into markdown.

Install upndown

As with node-readability, perform an npm install in the urlToMd directory.

npm install --save upndown

Generate markdown

Create type definitions

As with node-readability, upndown does not have type definitions available. Start by creating them in upndown.d.ts (GitHub link).

declare module "upndown" {
  class upndown{
    convert(source: string, callback: (err: Error, markdown: string) => any): void;
  }
  namespace upndown {}
  export = upndown
}

Add a reference to the type definitions below the readability reference.

/// <reference path="readability.d.ts"/>

Create the function

Start by importing the upndown module.

import * as upndown from 'upndown'

Next, create a new instance of upndown.

const und = new upndown()

Then create a function to convert the readable html to markdown.

const toMarkdown = (source: string): Promise<string> => {
  return new Promise((resolve, reject) => {
    und.convert(source, (err: Error, mkd: string) => {
      if (err) {
        return reject(err)
      }
      resolve(mkd)
    })
  }
)}

Update the handler

Finally, update the handler to incorporate the markdown conversion and return it.

export const handler = async (event: MarkdownEvent, context: Object, cb: Function) => {
  console.info('event received...', JSON.stringify(event))

  console.info('making url readable...')
  let article: readability.ReadableArticle, mkd: string
  try {
    article = await makeReadable(event.url)
  } catch (e) {
    return cb(e)
  }

  console.info('converting to markdown...')
  try {
    mkd = await toMarkdown(article.content)
  } catch (e) {
    return cb(e)
  }

  cb(null, {
    title: article.title,
    content: mkd
  })

  // Clean up readable article
  article.close()
}

See the finished handler.ts file on GitHub.

Test your code

An npm test should provide you with 2 passing tests!

Run the Lambda locally

Run serverless function run (from within the urlToMd directory) to see the new JSON response.

Deploy it

As the endpoint configuration has not changed, you can simply redeploy the function. Run serverless function deploy.

Once the function has deployed, refresh the endpoint to see the new JSON response.