rollup.utils.js

const path = require("path");
const fse = require("fs-extra");
const { version } = require("./packages/react-router/package.json");
const majorVersion = version.split(".").shift();

const PRETTY = !!process.env.PRETTY;

/**
 * Determine the relevant directories for a rollup build, relative to the
 * current working directory and taking LOCAL_BUILD_DIRECTORY into account
 *
 * ROOT_DIR     Root directory for the react-router repo
 * SOURCE_DIR   Source package directory we will read input files from
 * OUTPUT_DIR   Destination directory to write rollup output to
 *
 * @param {string} packageName  npm package name (i.e., @remix-run/router)
 * @param {string} [folderName] folder name (i.e., router). Defaults to package name
 */
function getBuildDirectories(packageName, folderName) {
  let ROOT_DIR = __dirname;
  let SOURCE_DIR = folderName
    ? path.join(__dirname, "packages", folderName)
    : path.join(__dirname, "packages", ...packageName.split("/"));

  // Update if we're not running from root
  if (process.cwd() !== __dirname) {
    ROOT_DIR = path.dirname(path.dirname(process.cwd()));
    SOURCE_DIR = process.cwd();
  }

  let OUTPUT_DIR = path.join(SOURCE_DIR, "dist");

  if (process.env.LOCAL_BUILD_DIRECTORY) {
    try {
      let nodeModulesDir = path.resolve(
        process.env.LOCAL_BUILD_DIRECTORY,
        "node_modules"
      );
      fse.readdirSync(nodeModulesDir);
      OUTPUT_DIR = path.join(nodeModulesDir, ...packageName.split("/"), "dist");
    } catch (e) {
      console.error(
        "Oops! You pointed LOCAL_BUILD_DIRECTORY to a directory that " +
          "does not have a node_modules/ folder. Please `npm install` in that " +
          "directory and try again."
      );
      process.exit(1);
    }
  }

  return { ROOT_DIR, SOURCE_DIR, OUTPUT_DIR };
}

function createBanner(packageName, version) {
  return `/**
 * ${packageName} v${version}
 *
 * Copyright (c) Remix Software Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE.md file in the root directory of this source tree.
 *
 * @license MIT
 */`;
}

// Babel plugin to replace `const REACT_ROUTER_VERSION = "0.0.0";` with the
// current version at build time, so we can set it on `window.__reactRouterVersion`
// for consumption by the Core Web Vitals Technology Report
function babelPluginReplaceVersionPlaceholder() {
  return function (babel) {
    var t = babel.types;

    const KIND = "const";
    const NAME = "REACT_ROUTER_VERSION";
    const PLACEHOLDER = "0";

    return {
      visitor: {
        VariableDeclaration: {
          enter: function (path) {
            // Only operate on top-level variables
            if (!path.parentPath.isProgram()) {
              return;
            }

            let { kind, declarations } = path.node;
            if (
              kind === KIND &&
              declarations.length === 1 &&
              declarations[0].id.name === NAME &&
              declarations[0].init?.value === PLACEHOLDER
            ) {
              path.replaceWith(
                t.variableDeclaration(KIND, [
                  t.variableDeclarator(
                    t.identifier(NAME),
                    t.stringLiteral(majorVersion)
                  ),
                ])
              );
            }
          },
        },
      },
    };
  };
}

// Post-build plugin to validate that the version placeholder was replaced
function validateReplacedVersion() {
  return {
    name: "validate-replaced-version",
    writeBundle(_, bundle) {
      Object.entries(bundle).forEach(([filename, contents]) => {
        if (!filename.endsWith(".js") || filename === "server.js") {
          return;
        }

        let requiredStrs = filename.endsWith(".min.js")
          ? [`{window.__reactRouterVersion="${majorVersion}"}`]
          : [
              `const REACT_ROUTER_VERSION = "${majorVersion}";`,
              `window.__reactRouterVersion = REACT_ROUTER_VERSION;`,
            ];

        requiredStrs.forEach((str) => {
          if (!contents.code.includes(str)) {
            throw new Error(
              `Expected ${filename} to include \`${str}\` but it did not`
            );
          }
        });
      });
    },
  };
}

// rollup.config.js
module.exports = {
  getBuildDirectories,
  createBanner,
  babelPluginReplaceVersionPlaceholder,
  validateReplacedVersion,
  PRETTY,
};