Laravel 5.4 mix version issue

I have a project that has about 10 javascript files. I want to use Laravel mix webpack to combine and version the js files. The files get combined but the versioning is not working. It only works for my scss files. It used to work in Laravel elixir. I checked the mix-manifest.json file in the public directory and this is what I found:

{
  "mix.js": "mix.b2328beb0372c051d06d.js",
  "/css/main.css": "/css/main.bb97b313cc88fe75b545.css",
  "/js/main.js": "/js/main.js"
}

I looked for the mix.js file and I could not find it anywhere in my project.

Here is my webpack.mix.js file:

mix.combine(
    [
        'resources/assets/js/jRespond.js',
        'resources/assets/js/sweetalert.min.js',
        ....
    ]
    , 'public/js/main.js')
    .sass('resources/assets/sass/main.scss', 'public/css/main.css')
    .version();

Thank you

via Chebli Mohamed