Bash.sh

npm install -g uglify-js clean-css-cli

settings-v2.json

{
    "filewatcher.commands": [
        {
          "match": "(?<!\\.min)\\.(js|css)$",
          "isAsync": true,
          "cmd": "minify ${file} > ${fileDirname}/${fileBasenameNoExt}.min${fileExtname}",
          "event": "onFileChange"
        }
    ]
}
    

settings.json

{
    "filewatcher.commands": [
        {
            // npm install uglify-js -g
            "match": "\\.js$",
            "notMatch": "\\.min\\.js$",
            "isAsync": true,
            "cmd": "uglifyjs ${file} -o ${fileDirname}/${fileBasenameNoExt}.min.js -c -m --verbose",
            "event": "onFileChange"
        },
        {
            // npm install clean-css-cli -g
            "match": "\\.css$",
            "notMatch": "\\.min\\.css$",
            "isAsync": true,
            "cmd": "cleancss -o ${fileDirname}/${fileBasenameNoExt}.min.css ${file}",
            "event": "onFileChange"
        }
    ]
}

I've recreated the VSCode settings file with the file watcher configuration. Now when you save any JS or CSS file in VSCode, it should automatically create or update the minified version. You can check the Output panel (View -> Output -> File Watcher) to see any errors or output from the minification process.