May 27, 2022

Using UnoCSS to Add SVG Icons

UnoCSS is a utility-first CSS framework, much like TailwindCSS, but much more pluggable.

It's so modular that you can UnoCSS's @unocss/preset-icons preset alone to handle icons only, and I was impressed by it, I mean, look at this, using SVG icons in pure CSS, only bundle what I use, how cool is that?

<!-- A basic anchor icon from Phosphor icons -->
<div class="i-ph-anchor-simple-thin" />
<!-- An orange alarm from Material Design Icons -->
<div class="i-mdi-alarm text-orange-400" />
<!-- A large Vue logo -->
<div class="i-logos-vue text-3xl" />
<!-- Sun in light mode, Moon in dark mode, from Carbon -->
<button class="i-carbon-sun dark:i-carbon-moon" />
<!-- Twemoji of laugh, turns to tear on hovering -->
  class="i-twemoji-grinning-face-with-smiling-eyes hover:i-twemoji-face-with-tears-of-joy"

unocss icons preset in action

It's incredibly cool, but I'm not yet ready to fully ditch TailwindCSS to migrate to UnoCSS, I'll start with the icons.

Another good thing about this is that I no longer need to inline SVG icons in my React component, currently, I'm just manually copying whatever SVG icons I want from as JSX into the app, it's somewhat a bad practice:

tweet from developit about svg

Adding UnoCSS to my Next.js app

Install the dependencies:

npm i @unocss/cli unocss @unocss/preset-icons -D

# any extra icon sets from iconify
# here use material design icons as an example
npm i @iconify-json/mdi -D

Configure uno.config.ts:

import { defineConfig } from "unocss"
import presetIcons from "@unocss/preset-icons"

export default defineConfig({
  presets: [presetIcons()],

Then create an npm script to generate CSS using UnoCSS's CLI:

"uno-generate": "unocss \"src/**/*.{ts,tsx}\" -o src/generated/uno.css"

I'm using Next.js, so I need to import the generated CSS in my src/pages/_app.tsx

import "../generated/uno.css"

To automate the uno-generate script, I created a webpack plugin and added it to next.config.js:

const spawn = require("cross-spawn")

class UnoCSS {
   * @param {import('webpack').Compiler} compiler
  apply(compiler) {
    compiler.hooks.beforeRun.tapPromise("unocss", async () => {
      spawn.sync("pnpm", ["uno-generate"], { stdio: "inherit" })
    let watching = false
    compiler.hooks.watchRun.tap("unocss", () => {
      if (watching) return
      watching = true
      spawn("pnpm", ["uno-generate", "--watch"], { stdio: "inherit" })

module.exports = {
  webpack(config) {
    config.plugins.push(new UnoCSS())
    return config

This plugin will make webpack run pnpm uno-generate before compiling your app, in development, it also runs in watch mode.

That's about it, I think I'll gradually move to UnoCSS, and replace my TailwindCSS @apply rules with UnoCSS shortcuts when I get some time.