@scalar/build-tooling/dist/rollup-options.js

Build tooling and helpers

import { readFileSync } from 'node:fs';
import alias from '@rollup/plugin-alias';
import json from '@rollup/plugin-json';
import typescript from '@rollup/plugin-typescript';
import yaml from '@rollup/plugin-yaml';
import copy from 'rollup-plugin-copy';
import css from 'rollup-plugin-import-css';
import emptyOutDir from './rollup-plugins/emptyOutDir.js';

/**
 * Generate rollup options for a Scalar package build
 *
 * This should be used for packages and libraries NOT bundling
 * projects to be served client-side (like web apps)
 *
 * Defaults:
 * - Treeshaking enabled
 * - Preserves modules
 * - Externalizes ALL dependencies
 */
function createRollupConfig(props) {
    /** Load the pkg file if not provided */
    const pkgFile = props.pkgFile ?? JSON.parse(readFileSync('./package.json', 'utf-8'));
    const plugins = Array.isArray(props.options?.plugins) ? [...props.options.plugins] : [];
    // Remove the ./dist folder by default
    if (props?.emptyOutDir !== false) {
        plugins.push(emptyOutDir({
            dir: './dist',
        }));
    }
    // Optional list of files to copy over
    if (props?.copy)
        plugins.push(copy({
            targets: props.copy,
            // Use the `generateBundle` hook to copy files, otherwise they are deleted by the `emptyOutDir` plugin
            hook: 'generateBundle',
        }));
    // For vanilla rollup (not Vite) we need to enable transpilation
    if (props.typescript)
        plugins.push(typescript());
    plugins.push(json());
    plugins.push(yaml());
    plugins.push(css());
    plugins.push(alias({
        entries: {
            '@': './src',
            '@test': './test',
        },
    }));
    const external = Array.isArray(props.options?.external) ? props.options.external : [];
    if ('dependencies' in pkgFile)
        external.push(...Object.keys(pkgFile.dependencies));
    if ('devDependencies' in pkgFile)
        external.push(...Object.keys(pkgFile.devDependencies));
    if ('peerDependencies' in pkgFile)
        external.push(...Object.keys(pkgFile.peerDependencies));
    return {
        treeshake: {
            annotations: true,
            preset: 'recommended',
            /**
             * We should never be importing modules for the side effects BUT
             * CSS import are by definition side effects. These must be excluded
             */
            moduleSideEffects: (id) => {
                return id.includes('.css');
            },
        },
        output: {
            format: 'esm',
            preserveModules: true,
            preserveModulesRoot: './src',
            dir: './dist',
        },
        ...props.options,
        // Do not bundle any dependencies by default.
        external: external.map((packageName) => new RegExp(`^${packageName}(/.*)?`)),
        plugins,
    };
}

export { createRollupConfig };