index.js

const fs = require("fs");
const path = require("path");
const AdmZip = require("adm-zip");
const core = require("@actions/core");

const files = core.getInput("files");
const dest = core.getInput("dest");
const recursive = core.getInput("recursive") === "true";

console.log(`Ready to zip "${files}" into ${dest}`);

const zip = new AdmZip();

files.split(" ").forEach(fileName => {
  const filePath = path.join(process.env.GITHUB_WORKSPACE, fileName);

  if (!fs.existsSync(filePath)) {
    console.log(`  - ${fileName} (Not Found)`);
    return;
  }

  const dir = path.dirname(fileName);
  const stats = fs.lstatSync(filePath);

  if (stats.isDirectory()) {
    const zipDir = dir === "." ? fileName : dir;
    zip.addLocalFolder(filePath, !recursive && zipDir);
  } else {
    const zipDir = dir === "." ? "" : dir;
    zip.addLocalFile(filePath, !recursive && zipDir);
  }

  console.log(`  - ${fileName}`);
});

const destPath = path.join(process.env.GITHUB_WORKSPACE, dest);

zip.writeZip(destPath);

console.log(`\nZipped file ${dest} successfully`);