Octo-composer

octo-composer is a minimalistic stand-alone middleware composing library for node.js.

Installation

npm install octo-composer

Usage

###Simple example

var compose = require('octo-composer').compose;

var middleware = compose([
  function (next) { console.log('Hello'); next(); },
  function (next) { console.log('World'); next(); }
]);

middleware();// Will print: HelloWorld

###Handling errors

var MiddlewareComposer = require('octo-composer').MiddlewareComposer;

var middleware = new MiddlewareComposer();
middleware.then(function(next) {console.log('Hello'); next()})
    .then(function(next) {throw new Error('Error!'); next();})
    .catch(function (err) {console.log(err.message);});

middleware.execute();// Will print: HelloError!

###Handling completion

var MiddlewareComposer = require('octo-composer').MiddlewareComposer;

var middleware = new MiddlewareComposer();
middleware.then(function(next) {console.log('Hello'); next();})
    .then(function(next) {console.log('World'); next();})
    .end(function () {console.log('!');});

middleware.execute();// Will print: HelloWorld!

###Passing parameters to middlewares

var MiddlewareComposer = require('octo-composer').MiddlewareComposer;

var middleware = new MiddlewareComposer();
middleware.then(function(a, b, next) {console.log(a + b); next();})
    .then(function(a, b, next) {console.log(a * b); next();});

middleware.execute(1, 2);// Will print: 32

API

new MiddlewareComposer()

Creates new middleware composer instance

MiddlewareComposer.then(middleware)

Adds middleware function to the composer.

MiddlewareComposer.end

Sets completion handler. The handler will be executed only if all middlewares were successfully run.

MiddlewareComposer.catch(handler)

Sets error handler. If any of middlewares throw an error MiddlewareComposer will stop executing the rest of middlewares and will call error handler instead.

MiddlewareComposer.execute(..args)

Executes all middlewares in the order they were added to the composer. All middlewares will receive next function as an additional parameter to the one that are passed to this method.

next function must be called in each of middlewares in order this to work.

compose(middlewares, onEnd, onError)

Returns function which can be used to execute composed middleware handler.