beyond/lib/engine/bundles/processors/svelte/extender/preprocessor/index.js

The Full Stack Universal Typescript Framework

const svelte = require('svelte/compiler');

module.exports = class extends global.ProcessorsExtenderSinglyPreprocessor {
    async _preprocessSource(source) {
        try {
            const extensions = new Map();

            let script;
            await svelte.preprocess(source.content, {
                script: ({content}) => (script = content) && void 0,
                style: ({content: code}) => extensions.set('sass', {code}) && void 0
            }, {filename: source.file});

            // Svelte components files export SvelteComponent as default
            let code = script ? `${script}\n\n` : '';
            code += `declare const Component: import('svelte/internal').SvelteComponent;\n` +
                'export default Component;'
            extensions.set('ts', {code});
            return {extensions};
        }
        catch (exc) {
            return {errors: [exc.message]};
        }
    }
}