Using with @rollup/plugin-multi-entry plugin and custom transform

[enes-kaplan]

Hello. I am new to rollup and its plugin usage and environment. Sorry if this already has a solution, I have not came across.

I have a library written in JS and some classes in TS. I have a custom transform plugin, which goes through all the needed JS files and combines/minifies in a single output file. This is what I wanted and all is good.

However, I also want to have my TS files compiled into JS as seperate modules. To handle multiple inputs, I've used @rollup/plugin-multi-entry plugin. This changed how I handled the transform plugin a little bit, due to loaded content being a list of files to be exported instead of singular input file's content. However, I cannot process the rest of my files once I return from transform. I get a .d.ts file per .ts file, but not the implementation codes. I get the implementation code correctly if I plain run it without my custom plugin for combining the dependencies. Here is the code:

import fs from "fs";
import path from "path";
import terser from "@rollup/plugin-terser";
import typescript from "@rollup/plugin-typescript";
import multi from "@rollup/plugin-multi-entry";

export default {
  input: ["javascript/src/js/lib.js", "javascript/test.ts"],
  output: [
    {
      file: "javascript/output/lib.js",
      format: "cjs", // es | cjs
      strict: false,
    },
    {
      file: "javascript/output/lib.min.js",
      format: "cjs", // es | cjs
      strict: false,
      plugins: [terser()],
    },
    {
      dir: "javascript/output",
      format: "cjs", // es | cjs
      preserveModules: true,
      preserveModulesRoot: "javascript",
    },
  ],
  plugins: [
    handleDependencies(),
    multi(),
    typescript({ tsconfig: "./tsconfig.json" }),
  ],
};

// Custom plugin to combine all files
function handleDependencies() {
  return {
    name: "handleDependencies",
    transform(content) {
      const splitContent = content.split("\n"); // each line is a file export like (export * from "D:\foo\bar.js")
      for (let i = 0; i < splitContent.length; i++) {
        const exportStatement = splitContent[i];
        const fileContent = readFileContent(exportStatement);
        if (exportStatement.includes("js-input.js")) {
          const deps = getDependencies(fileContent);
          const combined = combineDependencies(deps);
          return combined;
        }
      }
    },
  };
}

function readFileContent(exportStatement) {
  const filePath = exportStatement.match(/"(.*?)"/)[1];
  const content = fs.readFileSync(filePath, "utf8");
  return content;
}

// Find required files from entry file (lib.js)
// There are include statements in this js file to state library's modules, like "lib.include(filePath)"
// We get the list of files by matching them with regex
// Then read their content and combine them in combineDependencies method
function getDependencies(content) {
  let deps = content
    .match(/lib\.include\([^"']+["'](.*?)["']/gi)
    .map((str) => str.match(/lib\.include\([^"']+["'](.*?)["']/)[1]);
  deps = ["./js/lib.js"].concat(deps.slice(0));

  return deps;
}

// Combine all files' content to one output file
function combineDependencies(dependencies) {
  let code = "";
  for (const file of dependencies) {
    const filePath = path.join(process.cwd(), "/javascript/src/", file);
    const content = fs.readFileSync(filePath, "utf8");

    code += content;
  }

  return code;
}