routes.js

// Define the routes, which we will procedurally load
const routes =
{
	get: // body data not allowed in GET
	[
		{ path: '/', 										action: 'HelloWorld' 						},
		{ path: '/http', 									action: 'TestHTTP' 							},
		{ path: '/echo', 									action: 'EchoRequest' 						}, 
   ]
}

var gActions = {}

// Collect all route action definitions
var normalizedPath = require("path").join(__dirname, "routes"); // get the full path for the ./routes folder
require("fs").readdirSync(normalizedPath).forEach(function(file) { // run a function on each file name found in the ./routes folder

	console.log( `Found actions: ${file}` )
	var actions = require("./routes/" + file); // load the file by name out of the routes folder, as javascript
	var action_names = [] 
	actions.forEach( function( action ) // assume the module.exports for these files is an array of elements. Run a function on each element.
	{
		if ( gActions[action.action] ) // see if an action by this name was already found in another file
		{
			console.error( `Reimplementing action '${action.action}' in ${file} is not allowed` )
		}
		else
		{
			gActions[action.action] = action.run // save a reference to the function which should handle actions by this name
			action_names.push( action.action ) // only needed for the log print at the end, to have nice single-line output of all the actions
		}
	})
	console.log( ` - ${action_names.join(', ')}`)
});

// Apply to the express app
Object.keys(routes).forEach( function( method ) // for each method in the routes array, run a function
{ 
	routes[method].forEach( function(obj) // for each element in the array for this method, run a function
	{ 
		if ( !gActions[ obj.action ] ) // did we find a function to handle this action in the previous step?
		{
			console.warn( `No action found for ${method} '${obj.path}' with name '${obj.action}'` )
		}
		else
		{
			app[method]( obj.path, gActions[ obj.action ] ) // register this function with the express app
      // This works by using array lookup to call the 'get' function from app procedurally. So effectively, this is calling
      //   app.get( path, function handler )
		}
	}) 
})