example: unassert but preserve comments

babel.config.js

module.exports = function (api) {
  const presets = [];
  const plugins = [];
  let retainLines = false;
  let comments = true;

  if (api.env('production')) {
    plugins.push('babel-plugin-unassert');
    retainLines = true;
  }

  return {
    comments,
    retainLines,
    presets,
    plugins
  };
};

calc.js

/**
 * unassert example with Babel7
 *
 * Copyright (c) 2019 Takuto Wada
 * Licensed under the MIT license.
 *   http://twada.mit-license.org/
 */
'use strict';

// will be removed under production
const assert = require('assert');

/**
 * adds augend and addend
 *
 * @param {number} augend - the one to which the others are added
 * @param {number} addend - a quantity to be added to another
 * @return {number} - result of caluclation
 */
function add (augend, addend) {
  // checking augend
  assert(!isNaN(augend));
  /**
   * checking addend
   */
  assert.ok(!isNaN(addend));
  return augend + addend;
}

module.exports = {
    add
};

output

$ npm run gen:prod

> [email protected] gen:prod /path/to/pd-preserve-comment-unassert
> BABEL_ENV=production babel calc.js

/**
 * unassert example with Babel7
 *
 * Copyright (c) 2019 Takuto Wada
 * Licensed under the MIT license.
 *   http://twada.mit-license.org/
 */
'use strict';

// will be removed under production


/**
 * adds augend and addend
 *
 * @param {number} augend - the one to which the others are added
 * @param {number} addend - a quantity to be added to another
 * @return {number} - result of caluclation
 */
function add(augend, addend) {
  // checking augend

  /**
   * checking addend
   */

  return augend + addend;
}

module.exports = {
  add };

$ 

package.json

{
  "name": "pd-preserve-comment-unassert",
  "description": "preserve comment example",
  "version": "1.0.0",
  "author": {
    "name": "Takuto Wada",
    "email": "[email protected]",
    "url": "https://github.com/twada"
  },
  "devDependencies": {
    "@babel/cli": "^7.0.0",
    "@babel/core": "^7.0.0",
    "babel-plugin-unassert": "^3.0.0"
  },
  "keywords": [],
  "license": "MIT",
  "main": "index.js",
  "private": true,
  "scripts": {
    "gen:dev": "babel calc.js",
    "gen:prod": "BABEL_ENV=production babel calc.js"
  }
}