Using Static Class Methods To Generate Concrete Instances Of Abstract Classes In JavaScript And Node.js

test.js

class AbstractThing {

	// ---
	// ABSTRACT METHODS.
	// ---

	doThis() {
		throw( new Error( "Abstract method." ) );
	}

	doThat() {
		throw( new Error( "Abstract method." ) );
	}

	// ---
	// PUBLIC METHODS.
	// ---

	execute() {
		this.doThis();
		this.doThat();
	}

	// ---
	// STATIC METHODS.
	// ---

	// I provide a way to create a concrete implementation of the AbstractThing class
	// by providing the concrete functions. This is in lieu of creating a base class that
	// extends the AbstractThing class explicitly.
	static usingFunctions({ doThis, doThat }) {

		var implementation = new AbstractThing();

		// Override the abstract methods with the given concrete functions.
		implementation.doThis = doThis;
		implementation.doThat = doThat;

		return( implementation );

	}

}

// ----------------------------------------------------------------------------------- //
// ----------------------------------------------------------------------------------- //

// Create a concrete instance using the two concrete methods (no base class needed).
var thing = AbstractThing.usingFunctions({
	doThis: function() {
		console.log( "... do this." );
	},
	doThat: function() {
		console.log( "... do that." );
	}
});

console.log( "Is instance of AbstractThing:", ( thing instanceof AbstractThing ) );
thing.execute();