api_and_web_routes.js

//[normal webapp routes here]


var apiAuth = function(req,res,next) {
  ///...
	req.api = true;
	//...
	next();
};

app.all("/api/*",apiAuth);

var actions = {
		list:{
			POST:"create",
			GET:"index"
		},
		item:{
			GET:"view",
			PUT:"update",
			DELETE:"delete"
		}
	};

var routeApi = function(type,req,res,next) {
	var action = actions[type][req.method];
	if(!action) {
		res.send(404);
		return;
	}
	var route = models[req.param.model][action];
	route(req,res,next);
};

app.all('/api/:model',function(req,res,next) {
	routeApi('list',req,res,next);
});

app.all('/api/:model/:id',function(req,res,next) {
	routeApi('item',req,res,next);
});

app.all("*",function(req,res) {
	//make sure res and payload were defined in the route logic
	if(res.payload && res.method) {
		//if its an api call, we're going to want to always send json
		if(req.api) {
			//if its the render method, remove the first param which will be the view file
			if(res.method === 'render')
				res.payload.shift();
			res.json(res.payload);
			return;
		}
		//otherwise we can proceed this way
		res[res.method].apply(null,res.payload);
	} else {
		res.send(500);
	}
});