The cause: This issue occurs because the test1.js file’s javascript source code syntax is not supported by Browserify. The JS code may be written in ES6+ style. Solution: Therefore, you ought to use Babel to transcompile the javascript code to a lower syntax that Browserify accepts, like es2015. It can fix the error parseerror: ‘import’ and ‘export’ may appear only with ‘sourcetype: module’.

1. Set up the Babel Modules. – To generate a package.json file in the current folder, open a terminal and execute the command npm init. – To install the plugin modules, execute the command npm install –save-dev @babel/core @babel/cli @babel/preset-env in the terminal. – To verify the module installation, use the commands npm list @babel/core, npm list @babel/cli, and npm list @babel/preset-env. – The aforementioned babel plugin modules are also included in the project’s package.json file like the following:

   {
   "name": "browserify",
   "version": "1.0.0",
   "main": "index.js",
   "scripts": {
   "test": "echo "Error: no test specified" && exit 1"
   },
   "author": "",
   "license": "ISC",
   "description": "",
   "devDependencies": {
   "@babel/cli": "^7.17.10",
   "@babel/core": "^7.18.2",
   "@babel/preset-env": "^7.18.2"
   }
   }

2. Make a Babel configuration file. – Make a babel.config.json configuration file in the project directory. – The file babel.config.json should now contain the JSON source code below.

   {
   "presets": [
   [
   "@babel/preset-env",
   {
   /*
   Define the targets web browsers.
   You can ignore this settings for all web browsers.
   
   "targets": {
   "edge": "17",
   "firefox": "60",
   "chrome": "67",
   "safari": "11.1"
   },
   */
   "useBuiltIns": "usage",
   "corejs": "3.6.5"
   }
   ]
   ]
   }

3. Transcompile different JavaScript source files into one by using the Babel command. – Execute the command./node modules/.bin/babel js -out-dir lib in the project folder from the terminal. – The aforementioned command will transcompile all of the javascript files in the js folder to the lib folder and create a lib folder in the current project folder.

   ├─js
   │  ├─test1.js
   │  └─test2.js
   ├─lib
   │  ├─test1.js
   │  └─test2.js

   – The javascript source code for the files lib/test1.js and lib/test2.js may be seen on an earlier web browser by opening them in a text editor.