Javascript Module Pattern that returns a function (instead of an object) which contains other functions...

module_pattern.js

{
    let Module = (function() {
        let privateMethod1 = function() {
            console.log("FOO");
        };

        let privateMethod2 = function() {
            console.log("BAR");
        };

        let privateMethod3 = function() {
            console.log("TEA");
        };

        let constructor = function(msg) {
            console.log(msg);
        };

        return Object.assign(constructor, {
            publicMethod1: privateMethod1,
            publicMethod2: privateMethod2,
        });
    })();

    Module.extension1 = function(msg) {
        this(msg); // prints passed argument string (i.e 'Hello goodbye')
        this.publicMethod1(); // prints 'FOO'
        this.publicMethod2(); // prints 'BAR'
        this.privateMethod3(); // Not exposed, so results in -> Uncaught TypeError: Module.privateMethod3 is not a function ...
    };

    Module('Hello world'); // prints 'Hello world'
    Module.publicMethod1(); // prints 'FOO'
    Module.publicMethod2(); // prints 'BAR'
    Module.extension1('Hello goodbye'); // prints 'Hello goodbye', 'FOO' and 'BAR'
    Module.privateMethod3(); // Not exposed, so results in -> Uncaught TypeError: Module.privateMethod3 is not a function ...
}