// --- main.js ---

// Will only hot reload after this
require('node-hot')
    // Globally configure node-hot (optional)
    .configure({
        // Disable logging (default: false)
        silent: true,

        // Automatically patch all exported classes (default: false)
        patchExports: true,

        // Exclude patterns (default: node_modules)
        exclude: [
            /[\/\\]node_modules[\/\\]/,
            /[\/\\]bower_components[\/\\]/,
            /[\/\\]jspm_packages[\/\\]/
        ]
    });

// Main/entry module can't be reloaded, hence the extra file
require('./app');

// --- app.js ---

class Foo {}
let foo;

if (module.hot) {
    // Reload this module and its dependencies, when they change (optional)
    module.hot.accept();

    // Gets called before reload (optional)
    module.hot.store(stash => {
        stash.foo = foo;
    });

    // Gets called after reload, if there was a store (optional)
    module.hot.restore(stash => {
        foo = stash.foo;
    });

    // Replaces class methods and accessors (optional)
    module.hot.patch(Foo);
}

if (!foo) {
    foo = new Foo();
}