co-middleware

co-powered middleware mixin for objects

Installation

npm install co-middleware

API

Middleware(obj)

The Middleware may be used as a mixin or a standalone object.

Standalone:

var Middleware = require('co-middleware');
var middleware = new Middleware();

middleware.middleware('say', function *(message) {
  yield delay(200);
  console.log("I say: " + message);
  return true;
});

co(function *() {
  var result = yield middleware.run('say', 'hello')
});
// result == true, and console.logs "I say: hello""

Mixin:

var user = { name: 'Tobi' };
Middleware(user);
user.run('some middleware');

Prototype mixin:

var User = function() {
  this.name = 'Tobi';
};

Middleware(User.prototype);

var user = new User();
user.run('some middleware');

Middleware#middleware(name, fn*, [...moreFns*])

Registers generator as a middleware for name.

fn* can be:

• a generator function
• an array of multiple generator functions (will be run in the order passed in)

var middleware = new Middleware();
var middlewareA = function *() {},
    middlewareB = function *() {},
    middlewareC = function *() {};

// All of these would be equal

middleware.middleware(middlewareA);
middleware.middleware(middlewareB);
middleware.middleware(middlewareC);

// or

middleware.middleware([middlewareA, middlewareB, middlewareC]);

// or

middleware.middleware(middlewareA, middlewareB, middlewareC);

Middleware#run(name, ...args)

Runs the registered middlewares for name. Passes in optional args to the middlewares. args can be an array, or multiple arguments.

Returns a thunk.

var result = yield middleware.run('add', 2, 2);
console.log(result) // 4

Middleware chaining

As is implied by the middleware pattern, results from one middleware can be piped into the next. For example:

var middleware = new Middleware();

var uppercase = function *(str) {
  return str.toUpperCase();
};

var firstChar = function *(str) {
  return str.charAt(0)
};

middleware.middleware('upperFirst', uppercase, firstChar);

var result = yield middleware.run('upperFirst', 'hello world');
// result == 'H'

If you do not return a value, it will use the initial arguments passed in.

Middleware#removeMiddleware([name], [middleware])

Removes a given middleware for a specific name.

• If no name is provided, all middleware will be removed.
• If no middleware is provided, all middleware for given name will be removed.
• If name and middleware provided, removes middleware from name

Middleware#hasMiddlewares(name)

Returns whether or not any middleware exist for name.

Middleware#middlewares(name)

Returns an array of all middleware for a given name. If no middlewares exist, returns an empty array.