Error: [object Object] is not a PostCSS plugin

Question

This is my postcss configuration code in rollup.config.js file:

const postcssUrlOpts = [
    {
        url: 'copy',
        filter: /\.woff$/,
        assetsPath: 'font'
    }
];

const postcssOpts = {
    extract: 'index.css',
    plugins: [
        postcssUrl(postcssUrlOpts)
    ]
};

And this is the log that I get:

Error: [object Object] is not a PostCSS plugin
    at Processor.normalize (/.../node_modules/rollup-plugin-postcss/node_modules/postcss/lib/processor.es6:130:15)
    at new Processor (/.../node_modules/rollup-plugin-postcss/node_modules/postcss/lib/processor.es6:38:25)
    at postcss (/.../node_modules/rollup-plugin-postcss/node_modules/postcss/lib/postcss.es6:34:10)
    at /.../node_modules/rollup-plugin-postcss/dist/index.js:213:28
    at Generator.next (<anonymous>)
    at asyncGeneratorStep (/.../node_modules/rollup-plugin-postcss/dist/index.js:19:24)
    at _next (/.../node_modules/rollup-plugin-postcss/dist/index.js:41:9)

Without postcssUrl plugin all my css imports in javascript files are working and everything is fine but when I add this plugin to the list of postcss plugins I get this error in my console. Any other plugin like tailwindcss plugin works just fine.

versions:

postcss: ^8.1.10
postcss-url: ^10.1.1

Answer 1

The elements of the plugins array should be functions. You're calling the function immediately and returning the object. Wrap the function call in a function.

const postcssOpts = {
    extract: 'index.css',
    plugins: [
        () => postcssUrl(postcssUrlOpts)
    ]
};