Tip #1410: 50 Shades of Regex

I usually don’t drool over code but this one is just way too elegant for me not to. StackEdit – In-browser Markdown editor is an awesome app for markdown editing. One of the standout features is ability to comment and review – something sorely missing from the standard markdown. StackEdit very cleverly serializes reviews and notes as a base64 string and inserts it at the end of the document using HTML comment <!– –>. As part of the exercise this comment is saved very tidily in a 50 char wide column. So how does one wrap a string at a fixed width? This is the genius line:

const serializedData = 
  utils.encodeBase64(JSON.stringify(data))
    .replace(/(.{50})/g, '$1\n');

What does it do?

  • utils.encodeBase64(JSON.stringify(data)) – take our data object, serialize it to string, then convert to base64 to make sure it’s printable
  • replace – that’s just replace one thing with another
  • (.{50}) – a group of 50 characters
  • /g – global, i.e. do not stop after the match
  • '$1\n' – replace those groups of 50 characters with themselves plus newlines

Is that a brilliant piece of code or what? 🤤

Cover photo by Ono Kosuki from Pexels

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