Svelte Preprocess Chain utility

Purpose

The documentation about the preprocess function of svelte, says:

Multiple preprocessors can be used together. The output of the first becomes the input to the second. markup functions run first, then script and style.

But there are some cases where you need to run a preprocessor entirely before to run the next one. For example when you need to compile from any language to the basics (HTML, JS, CSS) and then perform other changes.

For that reason I created this package to basically run preprocess for every preprocessor you set.

Install

pnpm i -D svelte-preprocess-chain

Usage

This is the scenario I faced to create this package. Translate TypeScript to HTML and Less/SASS/SCSS/Stylus/PostCSS to CSS with svelte-preprocess and then some ajustment for Svelte Native with svelte-native-preprocessor (it uses svelte.parse which only supports JavaScript).

// import it
const sveltePreprocessChain = require("svelte-preprocess-chain");

// prepare your preprocessors chain
preprocessors = [
    sveltePreprocess(),
    svelteNativePreprocessor(),
];

// Then use this as the preprocess parameter
sveltePreprocessChain(preprocessors)

i.e. Webpack config file:

module.exports = {
    //...
    module: {
        rules: [
            //...
            {
                test: /\.svelte$/,
                exclude: /node_modules/,
                use: [
                    {
                        loader: 'svelte-loader-hot',
                        options: {
                            preprocess: sveltePreprocessChain(preprocessors),
                            hotReload: true,
                            hotOptions: {
                                native: true
                            }
                        }
                    }
                ]
            }
        ]
    }
}