add standlone protoc-gen-js npm package (@protocolbuffers/protoc-gen-js) for convenience

Author: dibenede

protoc_plugin/.gitignore

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+node_modules/
+bin/protoc-gen-js*
+protocolbuffers-protoc-gen-js-*.tgz

protoc_plugin/LICENSE.md

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+BSD 3-Clause License
+
+Copyright (c) 2025, Google Inc.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

protoc_plugin/bin/.gitkeep

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+#!/usr/bin/env node
+
+const child_process = require("child_process");
+const PLUGIN = require("./");
+
+child_process
+  .spawn(PLUGIN, process.argv.slice(2), { stdio: "inherit" })
+  .on("exit", (code) => process.exit(code));

protoc_plugin/cli.js

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+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+const AdmZip = require('adm-zip');
+
+const VERSION = '4.0.0';
+const BIN_DIR = path.join(__dirname, 'bin');
+
+const SUPPORTED_PLATFORMS = [
+    { platform: 'linux', arch: 'x86_64' },
+    { platform: 'linux', arch: 'aarch64' },
+    { platform: 'osx', arch: 'x86_64' },
+    { platform: 'osx', arch: 'aarch64' },
+    { platform: 'windows', arch: 'x86_64' },
+];
+
+function getDownloadUrl(platform, arch) {
+  return `https://github.com/protocolbuffers/protobuf-javascript/releases/download/v${VERSION}/protobuf-javascript-${VERSION}-${platform}-${arch}.zip`;
+}
+
+function unzip(zipFile, destDir, binaryName) {
+  return new Promise((resolve, reject) => {
+    const binaryPathInZip = `bin/${binaryName}`;
+    const zip = new AdmZip(zipFile);
+    const entry = zip.getEntry(binaryPathInZip);
+    if (entry) {
+      zip.extractEntryTo(entry, destDir, false, true);
+      resolve();
+    } else {
+      reject(new Error(`Binary ${binaryPathInZip} not found in zip file.`));
+    }
+  });
+}
+
+function getCurrentPlatform() {
+    const platform = os.platform();
+    if (platform === 'darwin') {
+        return 'osx';
+    }
+    if (platform === 'win32') {
+        return 'windows';
+    }
+    return 'linux';
+}
+
+function getCurrentArch() {
+    const arch = os.arch();
+    if (arch === 'x64') {
+        return 'x86_64';
+    }
+    if (arch === 'arm64') {
+        return 'aarch64';
+    }
+    return arch;
+}
+
+async function main() {
+  try {
+    await fs.promises.mkdir(BIN_DIR, {recursive: true});
+
+    const platform = getCurrentPlatform();
+    const arch = getCurrentArch();
+
+    const supportedPlatform = SUPPORTED_PLATFORMS.find(p => p.platform === platform && p.arch === arch);
+
+    if (!supportedPlatform) {
+      console.error(`Unsupported platform: ${platform} ${arch}`);
+      process.exit(1);
+    }
+
+    const downloadUrl = getDownloadUrl(supportedPlatform.platform, supportedPlatform.arch);
+    const zipFile = path.join(__dirname, `google-protobuf-${supportedPlatform.platform}-${supportedPlatform.arch}.zip`);
+    const isWindows = supportedPlatform.platform === 'windows';
+    const binaryName = isWindows ? 'protoc-gen-js.exe' : 'protoc-gen-js';
+    const binaryPath = path.join(BIN_DIR, binaryName);
+
+    console.log(`Downloading ${downloadUrl}`);
+    const response = await fetch(downloadUrl);
+    if (!response.ok) {
+        throw new Error(
+            `Failed to download: ${response.status} ${response.statusText}`
+        );
+    }
+    const buffer = await response.arrayBuffer();
+    await fs.promises.writeFile(zipFile, Buffer.from(buffer));
+
+    console.log('Unzipping...');
+    await unzip(zipFile, BIN_DIR, binaryName);
+
+    await fs.promises.unlink(zipFile);
+
+    console.log(`Making ${binaryPath} executable...`);
+    if (!isWindows) {
+        await fs.promises.chmod(binaryPath, 0o755);
+    }
+
+    console.log('Done!');
+  } catch (err) {
+    console.error(`Failed to install protoc-gen-js: ${err.message}`);
+    process.exit(1);
+  }
+}
+
+main();

protoc_plugin/download-protoc-gen-js.js

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+const path = require("path");
+const BIN_DIR = path.resolve(__dirname, "bin");
+const EXT = process.platform === "win32" ? ".exe" : "";
+
+module.exports = path.resolve(BIN_DIR, "protoc-gen-js" + EXT);

protoc_plugin/index.js

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+{
+  "name": "@protocolbuffers/protoc-gen-js",
+  "version": "4.0.0",
+  "description": "Standalone distribution of the protoc-gen-js plugin for Protocol Buffers",
+  "author": "Google Protocol Buffers Team",
+  "license": "BSD-3-Clause",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/protocolbuffers/protobuf-javascript.git"
+  },
+  "type": "commonjs",
+  "main": "index.js",
+  "bin": {
+    "protoc-gen-js": "cli.js"
+  },
+  "scripts": {
+    "postinstall": "node download-protoc-gen-js.js"
+  },
+  "dependencies": {
+    "adm-zip": "^0.5.16"
+  },
+  "engines": {
+    "node": ">=18.0.0"
+  }
+}