Refactor + add more tests (Part 2)

[endiliey]

Changes

Add babel-register on versions.js and write-translations.js to enable transpiling ES6

Fix #851

Refactor duplicate finding docs file logic in server.js and generate.js as function getFile + add test for it

https://github.com/facebook/Docusaurus/blob/03e237abda0600768d29be9d1cb50c6fb7ddd31b/lib/server/generate.js#L86-L102
https://github.com/facebook/Docusaurus/blob/03e237abda0600768d29be9d1cb50c6fb7ddd31b/lib/server/server.js#L172-L189

Refactor the logic to find metadata to be more declarative & efficient

Before
https://github.com/facebook/Docusaurus/blob/03e237abda0600768d29be9d1cb50c6fb7ddd31b/lib/server/server.js#L156-L161
https://github.com/facebook/Docusaurus/blob/03e237abda0600768d29be9d1cb50c6fb7ddd31b/lib/server/server.js#L165

After

const metadata = Metadata[Object.keys(Metadata).find(id => Metadata[id].permalink === url)];

Refactor duplicate getting docs component logic in server.js and generate.js to a new file docs.js as function getComponent

https://github.com/facebook/Docusaurus/blob/03e237abda0600768d29be9d1cb50c6fb7ddd31b/lib/server/server.js#L195-L247
https://github.com/facebook/Docusaurus/blob/03e237abda0600768d29be9d1cb50c6fb7ddd31b/lib/server/generate.js#L110-L143

Changed the way we replace any links to markdown files to their website html links + ADD TEST

Note that mdToHtml is the mapping of a markdown to it's respective html link.
mdToHtml keys ~ number of docs

const mdToHtml = {
  'doc1.md': 'docs/en/next/doc1.html',
  'doc2.md': 'docs/en/next/doc2.html',
  'doc3.md': 'docs/en/next/doc3.html',
  'doc4.md': 'docs/en/next/doc4.html',
}

Before
It will try every possible mdToHtml key and try to replace that key with the corresponding website html links. Lot of time wasted building htmlLink from mdLink that might not exist on that file as well

Time Complexity ~ O(number of mdHtml keys)

https://github.com/facebook/Docusaurus/blob/03e237abda0600768d29be9d1cb50c6fb7ddd31b/lib/server/generate.js#L115-L131

After
It will try to find all the markdown links in a file and try to replace it with the corresponding website html links.

Time Complexity ~ O(number of unique markdown links in a file)

function mdToHtmlify(oldContent, mdToHtml, metadata) {
  let content = oldContent;
  const mdLinks = [];
  
  // find any links to markdown files
  const regex = /(?:\]\()(?:\.\/)?([^'")\]\s>]+\.md)/g;
  let match = regex.exec(content);
  while (match !== null) {
    mdLinks.push(match[1]);
    match = regex.exec(content);
  }

  // replace to their website html links 
  new Set(mdLinks).forEach(mdLink => {
    let htmlLink = mdToHtml[mdLink];
    if (htmlLink) {
      htmlLink = getPath(htmlLink, siteConfig.cleanUrl);
      htmlLink = htmlLink.replace('/en/', `/${metadata.language}/`);
      htmlLink = htmlLink.replace(
        '/VERSION/',
        metadata.version && metadata.version !== env.versioning.defaultVersion
          ? `/${metadata.version}/`
          : '/'
      );
      content = content.replace(
        new RegExp(`\\]\\((\\./)?${mdLink}`, 'g'),
        `](${htmlLink}`
      );
    }
  });
  return content;
}

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

1. Test Locally

yarn start

Links still work as per normal

2. Test in netlify
   https://deploy-preview-854--docusaurus-preview.netlify.com/

Related PRs

#847

[docusaurus-bot]

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Built with commit 64cb4f3

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[yangshun]

@endiliey You deserve a medal 🏅