postcss8 support for nuxt 2.15+

Since nuxt@2.15 nuxt supports opting-in to use postcss@8 (via nuxt/nuxt.js#8546).

Upgrade is pending for csstools/postcss-preset-env#191 (see nuxt/nuxt.js#8087 and nuxt/nuxt.js#8408)

In the meantime, this module allows rapid migration:

• Ensures supported nuxt version is used (>= 2.15.3)
• Forces to use upgraded dependencies using __NUXT_PREPATHS__
• Will be updated accordingly to self-disable when a nuxt version with default postcss8 detected
• Use autoprefixer instead of postcss-preset-env

Usage

Install nuxt-postcss8 as devDependency:

1yarn add --dev nuxt-postcss8
2# or
3npm i -D nuxt-postcss8

Add nuxt-postcss8 to buildModules in nuxt.config:

1// nuxt.config
2export default {
3  buildModules: [
4    'nuxt-postcss8'
5  ]
6}

For module authors

If you have a nuxt module that requires postcss@8, install postcss@8 and nuxt-postcss8 as dependency:

1yarn add postcss@8 nuxt-postcss8
2# or
3npm i postcss@8 nuxt-postcss8

Inside module:

1export default async function() {
2  await this.addModule(require('nuxt-postcss8'))
3}