terser.js

#!/usr/bin/env node

/**
 * Minifies a file with existing sourcemap with terser.
 *
 * arg1 {string} file to minify
 * arg2 {string} output file
 */

const fs = require("fs");
const path = require("path");
const assert = require("assert");
const terser = require("terser");
const moment = require("moment");
const commenting = require("commenting");
const version = require("./package.json").version;

assert(process.argv.length >= 4, "./terser <input> <output> <preamble>");

const inFilename = process.argv[2];
const outFilename = process.argv[3];

const preamble = `react-msa-viewer ${version}
Copyright ${moment().format("YYYY")}, Plotly, Inc.
All rights reserved.
Licensed under the MIT license.
Generated: ${moment().format("YYYY-MM-DD")}
Version: ${version}
Source: https://github.com/plotly/react-msa-viewer`;

const options = {
  compress: {
    passes: 2,
  },
  mangle: true,
  sourceMap: {
    content: fs.readFileSync(inFilename + ".map", "utf8"),
    url: path.basename(outFilename) + ".map",
  },
  output: {
    beautify: false,
    preamble: commenting(preamble.trim(), { extension: ".js" }),
  },
};
console.log(`./terser ${inFilename} -> ${outFilename}`);
const code = fs.readFileSync(inFilename, "utf8");
const result = terser.minify(code, options);
fs.writeFileSync(outFilename, result.code, "utf8");
fs.writeFileSync(outFilename + ".map", result.map, "utf8");