Skip to content

How to change image URLs in a markdown string

I was trying to see if moving my blog (based on Hugo) to Next.js was a good move (it wasn’t) and I found a problem.

Hugo allows me to use spaces in images, which is handy especially as I use screenshots and I get those named as Screen Shot 2022-... by default.

The Next.js markdown does not allow that. So I had a script that converted all images names to use hyphens instead of spaces

"Screen Shot 2022-..." 

=> 

"Screen-Shot-2022-..."

and then I replaced the post markdown content with that.

Also I had to change the URL because Hugo allows a post to be in the same folder as the markdown file, while Next.js does not.

So I used a /public/images/<SLUG>/ folder format to make each post image public.

Here’s how I did that:

import matter from 'gray-matter'

...

let { data: frontmatter, content } = matter(fileName)

const regex = /\!\[(.*?)\]\((.*?)\)/gm
let matches

while ((matches = regex.exec(content)) !== null) {
  content = content.replace(
      '](' + matches[2],
      `](/images/${slug}/${matches[2].replace(/ /g, '-').replace(/\//g, '')}`
  )
}

→ Get my JavaScript Beginner's Handbook

→ I wrote 17 books to help you become a better developer:

  • C Handbook
  • Command Line Handbook
  • CSS Handbook
  • Express Handbook
  • Git Cheat Sheet
  • Go Handbook
  • HTML Handbook
  • JS Handbook
  • Laravel Handbook
  • Next.js Handbook
  • Node.js Handbook
  • PHP Handbook
  • Python Handbook
  • React Handbook
  • SQL Handbook
  • Svelte Handbook
  • Swift Handbook
...download them all now!

Also, JOIN MY CODING BOOTCAMP, an amazing cohort course that will be a huge step up in your coding career - covering React, Next.js - next edition February 2025

Bootcamp 2025

Join the waiting list