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Roads

An isomophic web framework

The Roads.js isomorphic web framework

Roads is a simple web framework. It’s similar to Express.js, but has some very intentional design differences.

Why should I use Roads?

  1. Roads is isomorphic, which means you write code once and run it on a server or in a browser.
  2. Roads can be attached to any node HTTP server including the standard node HTTP server or Express.js.
  3. Roads can be run without being attaching to an HTTP server. This is great for writing tests, working with web sockets, or writing API first websites.

Build Status

Build status

Table of Contents

Getting Started

Building a project with roads is very straightforward.

  1. Create your Road object

    TypeScript

     import { Road } from 'roads';
 let road = new Road();

    JavaScript

     const { Road } = require('roads');
 let road = new Road();

  2. Add code to the road

    TypeScript

     import { Road } from 'roads';
 let road = new Road();

 road.use(function (method, path, body, headers) {
     console.log('A ' + method + ' request was made to ' + path);
 });

    JavaScript

     const { Road } = require('roads');
 let road = new Road();

 road.use(function (method, path, body, headers) {
     console.log('A ' + method + ' request was made to ' + path);
 });

  3. Run your code.

    • HTTP: The following examples show how easy it is to hook up an HTTP server with roads and roads-server, but you can also connect it to express.js or any other http server.

    TypeScript

     import { Server } from 'roads-server';

 const road = ...; // See steps 1 and 2 for road construction
 const server = new Server(road);
 server.listen(8080);

    JavaScript

     const { Server } = require('roads-server');

 const road = ...; // See steps 1 and 2 for road construction
 const server = new Server(road);
 server.listen(8080);

Now that you can interact with your ROad, continue reading the docs below for more information on routers, error handling, PJAX support and more!

Road

A Road is a container that holds an array of functions called the request chain. The request chain generally holds your routing logic and any pre or post processing instructions. You add to the request chain via the use method, and execute the request chain with the request method.

new Road()

Create a Road.

Creates a new Road object.

TypeScript

import { Road }from 'roads';
let road = new Road();

JavaScript

const { Road } = require('roads');
let road = new Road();

use(fn Function)

Add a custom function that will be executed with every request.

The use function can be called one or more times. Each time it is called, the function provided via the fn parameter will be added to the end of the request chain which is executed when you call request.

name type required description
fn Function(method: string, url: string, body: string, headers: object, next: function) yes This is the function that will be added to the end of the request chain. See the Middleware below for more details on the function parameters.

Middleware

Each function in the request chain is called middleware. Each middleware function must match the following function signature.

*function (method: *string, url: string, body: string, headers: object, next: next): Promise<Response string>**

Parameters | name | type | description | | ——- | —————————- | ———————————————————————————————— | | method | string | The request’s HTTP method | | url | string | The request’s URL. The SimpleRouter is included to help run different code for different URLs. | | body | string | The request’s body (as a string). To parse this check out the parseBodyMiddleware | | headers | object | The request’s headers. This is an object of strings or arrays of strings. | | next | function(): Promise<Response | String> | The next step of the request chain. If there are no more steps in the request chain this does nothing. This method will always return a promise, which resolves to a Response object, or a string. |

Each middleware function must return a promise that resolves to a Response object or a string. If you return a string it will be transformed into a response object using the default status code (200) and no headers.

// Simple example that sends a JSON response and doesn't continue through the request chain
road.use(function (method, url, body, headers, next) {
    return JSON.stringify({
        method: method,
        url: url,
        body: body,
        headers: headers
    });
});

// Simple async example that sends a JSON response and doesn't continue through the request chain
road.use(async function (method, url, body, headers, next) {
    let db_record = await myPromiseReturningDBCall();

    return JSON.stringify(db_record);
})


// Example of middleware that redirects the user if their url has a trailing slash, otherwise it
//	continues through the request chain
road.use(function (method, url, body, headers, next) {
    if (url.path != '/' && url.path[url.path.length - 1] === '/') {
        return new roads.Response(null, 302, {
            location: url.path.substring(0, url.path.length - 1)
        });
    }

    return next();
});

// Example of middleware that catches errors and returns a 500 status code
road.use(function (method, url, body, headers, next) {
    // Continue down the request chain, and only execute this middleware logic afterwards
    return next()
        // Catch any errors that are thrown by the resources
        .catch ((err) => {
            console.err(err);
            // Wrap the errors in response objects.
            return new roads.Response('Unknown error', 500);
        });
});

How do I control the order of my middleware?

Within your middleware function you can add logic that happens before you continue down the request chain, and after the request chain has finished executing.

road.use(function (method, url, body, params, next) {
    console.log('This happens at the start of a request, before we continue down the request chain');
    return next()
        .then((response) => {
            console.log('This happens later, after the request chain resolves');
        });
});

You can picture the logic path like a U. The following example assumes two functions have been added to the request chain.

Start of request for                End of request for
the first middleware                the first middleware
          |                                 / \
         \ /                                 |
Start of request for      ____ \    End of request for
the second middleware          /    the second middleware

As you add more functions to the request chain, it lengthens each arm of the U.

Context

Each middleware function has access to a request context through this. This context will be different for each request, but identical for each middleware in a request chain.

Note: Do not use arrow functions if you want to interact with this. You will not have access to the context if you use arrow functions, and it may have unintended side effects.

road.use(function (method, url, body, headers, next) {
    this.extraInfo = 'hello!';
    return next();
});

road.use(function (method, url, body, headers) {
    return new Response(this.extraInfo, 200);
});

road.request('GET', '/me').then((response) => {
    // This will log "hello!"
    console.log(response.body);
});

Middleware is encouraged to add variables to this context to simplify development. Make sure to namespace your variables to ensure there are no conflicts with other librares.

eg:

var road = new Road();
road.use(function (method, url, body, headers) {
    this.myProject_requireAuthentication = true;
});

You can also use the StoreValsMiddleware to ensure you don’t have conflicts with other middleware.

Typing your context

In Typescript you can define your context type with a generic.

road.use<{ hello: string }>(function (method, url, body, headers) {
	console.log(this.hello);
});

Many of the bundled middleware include their contexts, and you can merge them together with &.

road.use<StoreValsContext & CookieContext>(function (method, url, body, headers) {
	console.log(this.getCookies());
	console.log(this.getAllVals());
});

request(method: string, url: string, body?: string, headers?: object)

Locate and execute the resource method associated with the request parameters.

This function will execute the request chain in the order they were assigned via use and return a Promise that resolves to a Response

The parameters are all the standard HTTP request parameters.

Make sure to catch any errors in the promise!

let promise = road.request('GET', '/users/dashron');

promise.then((response) => {
    console.log(response);
});

promise.catch((error) => {
    // handle errors
});

Response

The response object contains all of the information you want to send to the client. This includes the body, status code and all applicable headers.

new Response(body: string, status?: number, headers?: object)

Constructor Create a response object.

name type description
body string The body of the response.
status number The HTTP Status code.
headers object All the headers. The value may be a string or an array of strings 
new Response("Hello!", 200, {"last-modified":"2014-04-27 00:00:00"});

Body

The raw JavaScript object returned by the request

console.log(response.body);

Status

The HTTP status returned by the request

console.log(response.status);

Headers

A JavaScript object of all response headers. The value might be a string or an array of strings

console.log(response.headers);

Bundled Middleware

Roads comes bundled with a handfull of middleware functions.

Cookies

Middleware to add some cookie management functions

The cookie middleware object has three important exported functions

serverMiddleware

Middleware to attach to your road via road.use.

This middleware will add any new cookies to the response object and thus is most useful server-side.

import { CookieMiddleware, Response, Road } from 'roads';

var road = new Road();
road.use(CookieMiddleware.serverMiddleware);

buildClientMiddleware(pageDocumenet: Document)

Creates a middleware function to attach to your road via road.use. This middleware will add the cookie to document.cookie, so it’s most useful to be used client side

import { CookieMiddleware, Response, Road } from 'roads';

var road = new Road();
road.use(CookieMiddleware.buildClientMiddleware(Document));

The Cookie Context represents the request context when either the server or client middleware are used. This context includes two functions.

When you’re using typescript you can pass this context to one of the middleware or route’s generics to get proper typing on the request context.

setCookie(name: string, value?: string, options?: object)

Calling this function will store your new cookies. The parameters directly map to the cookie module.

To remove a cookie, set the value to null.

These cookies will be automatically applied to the response after your request

import { CookieContext } from 'roads/types/middleware/cookieMiddleware';
import { CookieMiddleware, Response, Road } from 'roads';

var road = new Road();
road.use(CookieMiddleware.serverMiddleware);

road.use<CookieContext>(function (method, path, body, headers, next) {
    console.log(this.getCookies());

    this.setCookie('auth', 12345, {
        domain: 'dashron.com'
    });

    // The cookie middleware will automatically apply the Set-Cookies header to this response
    return new Response('Hello!', 200);
});

getCookies()

Returns an object with all the cookies. It defaults to all the request cookies, but merges anything applied via setCookie on top (i.e. setCookie will override the request cookie)

import { CookieContext } from 'roads/types/middleware/cookieMiddleware';
import { CookieMiddleware, Response, Road } from 'roads';

var road = new Road();
road.use(CookieMiddleware.serverMiddleware);

road.use<CookieContext>(function (method, path, body, headers, next) {
    console.log(this.getCookies());
});

CORS

Middleware to Apply proper cors headers

This middleware sets up everything you need for your server to properly respond to CORS requests.

The options object supports the following properties.

name type description
validOrigins array An array of origin urls that can send requests to this API
supportsCredentials boolean A boolean, true if you want this endpoint to receive cookies
responseHeaders array An array of valid HTTP response headers
requestHeaders array An array of valid HTTP request headers
validMethods array An array of valid HTTP methods
cacheMaxAge number The maximum age to cache the cors information 
import { CorsMiddleware, Road } from 'roads';

var road = new Road();
road.use(CorsMiddleware.build({
    validOrigins: ['http://localhost:8080'],
    responseHeaders: ['content-type']
}));

Parsing request bodies

Middleware to parse the request body

This middleware looks at the Content-Type header and uses that information to attempt to parse the incoming request body string. The body will be applied to the context field body.

import { ParseBodyContext } from 'roads/types/middleware/parseBody';
import { ParseBodyMiddleware, Response, Road } from 'roads';

var road = new Road();
road.use(ParseBodyMiddleware.middleware);

Parse Body Context

ParseBodyContext<BodyType> When using typescript you can pass this when adding middleware or routes to see proper typing on this.

This context specifically adds one variable body which will match the structure passed to the ParseBodyContext via the BodyType generic.

import { ParseBodyContext } from 'roads/types/middleware/parseBody';
import { ParseBodyMiddleware, Response, Road } from 'roads';

var road = new Road();
road.use(ParseBodyMiddleware.middleware);

road.use<ParseBodyContext<{
    name: string,
    description?: string
}>>(function (method, url, body, headers) {
    // body === string representation of the input. In this example, '{"name":"dashron"}'
    // this.body === parsed version of that representation. In this example, {"name": "dashron"}
    // this.body.name will be properly identified by typescript due to the generic BodyType passed to ParseBodyContext. In this example, "dashron"
});

road.request('POST', '/users', '{"name":"dashron"}', {"content-type": "application/json"});

Remove trailing slash

Middleware to kill the trailing slash on http requests

Exposes a single middleware function to remove trailing slashes in HTTP requests. This is done by redirecting the end user to the same route without the trailing slash.

When used, any url that ends with a trailing slash will immediately return a response object redirecting the client to the same url without the trailing slash (302 redirect with Location: [url_without_slash])

import { RemoveTrailingSlashMiddleware, Response, Road } from 'roads';

var road = new Road();
road.use(RemoveTrailingSlashMiddleware.middleware);

Basic router

This is a basic router middleware for roads. It allows you to easily attach functionality to HTTP methods and paths.

Here’s how you use it.

  1. Create your road (see Getting Started step 1)
  2. Create your Router
    import { SimpleRouterMiddleware } from 'roads';
	let road = // see getting started
    let router = new SimpleRouterMiddleware.SimpleRouter(road);
  1. Assign routes to the router
    // This is a simple route with no path variables
    router.addRoute('GET', '/posts', (url, body, headers) => {
        // url, body and headers are all identical to the values sent to functions in roads.use
    });

    // This route supports numeric variables
    router.addRoute('GET', '/posts/#post_id', (url, body, headers) => {
        // url.args.post_id will contain the integer from the URL.
        // e.g. GET /posts/12345 will have url.args.post_id === 12345
    });

    // This route supports any variable
    router.addRoute('GET', '/posts/$post_slug', (url, body, headers) => {
        // url.args.post_slug will contain the value from the URL.
        // e.g. GET /posts/my-post will have url.args.post_slug === 'my-ost'
    });

Note: This router supports the x-http-method-override header and _method query parameter on POST requests, which allow you to route to a different HTTP method than POST.

applyMiddleware(road: Road)

If you don’t provide a road to the SimpleRouter constructor, your routes will not be executed. If you have reason not to assign the road off the bat, you can assign it later with this function.

addRoute(method: string, path: string, fn: function)

This is where you want to write the majority of your webservice. The fn parameter should contain the actions you want to perform when a certain path and HTTP method are accessed via the road object.

Note: The function must not be an arrow function! If you use an arrow function you will not have access to the request context.

The path supports a very basic templating system. The values inbetween each slash can be interpreted in one of three ways

e.g. /users/#userId will match /users/12345, not /users/abcde. If a request is made to /users/12345 the route’s requestUrl object will include the key value pair of args: { userId: 12345 }

Any variables will be added to the route’s request url object under the “args” object.

    // This is a simple route with no URI variables
    router.addRoute('GET', '/posts', function (url, body, headers) {
        // url, body and headers are all identical to the values sent to functions in roads.use
    });

    // This route supports numeric variables
    router.addRoute('GET', '/posts/#postId', function (url, body, headers) {
        // url.args.postId will contain the integer from the URL.
        // e.g. GET /posts/12345 will have url.args.postId === 12345
    });

    // This route supports any variable
    router.addRoute('GET', '/posts/$postSlug', function (url, body, headers) {
        // url.args.postSlug will contain the value from the URL.
        // e.g. GET /posts/my-post will have url.args.postSlug === 'my-ost'
    });

Add route also supports the same context generics as road.use.

	router.addRoute<CookieContext>('GET', '/posts/$postSlug', function (url, boddy, headers) {
		console.log(this.getCookies());
	});

addRouteFile(filePath: string, prefix?: string)

Add an entire file worth of routes.

Parameter Type Description
filePath string the path of the file to load
prefix string the URL path prefix that these routes will be attached to

Example File:

{
    '/posts/#post_id': {
        'GET': (url, body, headers) => {

        }
    }
}

import { SimpleRouterMiddleware } from 'roads';
let road = // see getting started
let router = new SimpleRouterMiddleware.SimpleRouter(road);
router.addRouteFile('routes.js', '/users/');

If-Modified-Since caching

Middleware to easily manage caching via if-modified-since headers

Browsers automatically support a conditional caching mechanism via the if-modified-since header. It works as follows.

  1. When a browser loads a page the server has the option to send a last-modified header indicating the last time this page changed.
  2. If the last-modified header exists, the browser stores the contents of the page alongside the value of last-modified.
  3. The next time the browser loads that page it sends the last-modified time via the if-modified-since header.
  4. The server then compares the provided if-modified-since header to the time this page was last changed.
  5. If the if-modified-since header is newer than the last time the page was changed, the server returns a 304 status code with no body. This tells the browser to load the same contents it loaded last time.
  6. If the if-modified-since header is older than the last time the page was schanged, the server returns the page as expected.

You can read more on MDN.

This style of caching is most useful for static files such as your JavaScript or CSS files.

To use this middleware, add the following code.

import { ModifiedSinceMiddleware, Road } from 'roads';

var road = new Road();
road.use(ModifiedSinceMiddleware.middleware);

To get it working in your route, add the ModifiedSinceContext and the following couple of lines to your middleware or route.

road.use<ModifiedSinceMiddleware.ModifiedSinceContext>(function (method, url, body, headers) {
	const date = ...// `date` is the last time the page changed. For a file on the filesystem this means fs.statSync(filePath).mtime.
	if (this.checkModifiedSince(date)) {
		return this.buildNotModifiedResponse();
	}

The middleware will automatically return a last-modified header equal to the date value passed to checkModifiedSince.

checkModifiedSince(date: string | Date)

This function returns true if the date provideed is greater than the date in the if-modified-since header. False otherwise.

If date is a string, it should be a value that can be passed to the Date(string) constructor. See If-Modified-Since caching for an example of how to use this function.

buildNotModifiedResponse()

This function returns a 304 Response with no body. This is the proper response when the document has not been modified since the if-modified-since header. See If-Modified-Since caching for an example of how to use this function.

Middleware helpers

The documentation below covers additional generic middleware that are useful when creating new middleware, or other advanced topics.

Apply To Context

Middleware to apply a predefined value to the request context

This middleware is a one liner to assign a value to the context. It’s useful for making values easily available to each request, such as an api library.

In the future I hope to have automatic typing for this context, but I’m still thinking through how to pull that off. In the meanwhile you should create your own Context types.

import { ApplyToContext } from 'roads';
road.use(ApplyToContext.build('example', 'test'));

road.use<{ example: 'test' }>(function (method, url, body, headers) {
    console.log(this.example); // test
});

Reroute

Middleware that offers a function in the request context that allows you to easily interact with a road

In the following example, road and APIRoad are two different Road objects.

import { RerouteMiddleware, Road } from 'roads';
road.use(RerouteMiddleware.build('api', APIRoad));

road.use<{ api: Road['request'] }>(function (method, url, body, headers) {
    this.api('GET', '/users')
        .then((response) => {
            console.log(response);
        })
        .catch((error) => {
            console.log(error);
        });
});

Store Values

Middleware that helps you save arbitrary data inside of a request context

This middleware adds two functions, setVal(key, val) and getVal(key) for storing and retrieving arbitrary values.

import StoreValsMiddleware from 'roads/middleware/storeVals';
road.use(StoreValsMiddleware.middleware);

road.use(function (method, url, body, headers, next) {
    return next().then((response) => {
        console.log(this.getVal('page-title'));
    });
});

road.use(StoreValsMiddleware.middleware);

PJAX(road: Road, containerElement: DomElement, window: Window)

A helper object to easily enable PJAX on your website using roads

PJAX is a technique for speeding up webpages by automatically replacing links or form submission with AJAX calls. This allows for clean, quick page refreshes via JavaScript, with a simple fallback if JavaScript is disabled.

PJAX looks in the containerElement at each anchor tag with the data-roads-pjax="link" attribute and changes it from a normal link into a link that uses the road.

Name Type Description
Road road The road that will be used when clicking links
HTMLElement containerElement The element that will be filled with your roads output
Window window The page’s window object to help set page title and url 
<div id="container"></div>

var road = ...; // Incomplete. See the getting started section for more information about creating a road
var pjax = new require('roads').PJAX(road, document.getElementById('container'), window);
pjax.register();

PJAX.register()

This function call enables PJAX on the current page.

pjax.register();

PJAX.registerAdditionalElement(element: HTMLAnchorElement)

If you would like PJAX to work on links that are not within the container you must call this function. Additionally this function must be called before register

<div id="container"></div>
<a id="external-link" href="...">link</a>

var road = ...; // Incomplete. See the getting started section for more information about creating a road
var pjax = new require('roads').PJAX(road, document.getElementById('container'), window);
pjax.registerAdditionalElement(document.getElementById("external-link"));
pjax.register();

If you would like a link to run via PJAX instead of a new page load, add the following data attribute to that link.

data-roads-pjax="link"

e.g.

<a href="/home" data-roads-pjax="link">Home</a>

Note: The link must be within the container for this to work. If you want links outside the container to work you should use registerAdditionalElement

PJAX Form Format

If you would like a form to run via PJAX instead of a new page load, add the following data attributes to the relevant elements.

Form attributes

Submit button attributes

e.g.

    <form method="POST" action="/users/12345" data-roads-pjax="form">
        <!-- your form elements go here -->
        <input type="submit" value="Send message" data-roads-pjax="submit">
    </form>

PJAX Page titles

There are a couple of steps required to get page titles working properly with PJAX.

First you must use the storeVals middleware to manage your page title. In the following example we are storing a page title of "Homepage".

this.setVal('page-title', 'Homepage');

Second you should have your server-side rendering put this value into the <title> element of your layout. Check the typescript example for how that could work with the Handlebars templating engine.

Third you need to create your RoadsPJAX object and configure it to look for your page-title value.

PJAX Page Title Example

import { Road, RoadsPJAX } from 'roads';

const road = ...; // Incomplete. See the getting started section for more information about creating a road

const pjax = new RoadsPJAX(road);
pjax.addTitleMiddleware('page-title');
pjax.register(window, document.getElementById('container'));

Isomorphic PJAX tips

There’s a very easy pattern to follow to ensure sharing client and server code works successfully via PJAX. You can see this pattern in more detail in the examples folder

  1. Any route that is unsafe to be run in the browser should be kept in separate files from the rest.
  2. Create two initalization scripts. One for starting the server, and one that will be compiled and loaded in the browser.
  3. Compile the browser script to be run in the browser. Currently I recommend Browserify, and that’s how the typescript example works.
  4. Load the browser script on any server side page that should enable PJAX.

FAQ

Why is this called roads? The name Roads fit well with some of the earlier architectural decisions and some of the more advanced ways of using this feature. Over time those features have become less prominent but we kept the name.

Not good enough for you? Fine, I’ll make an awkward backronym. How about Requests Organized And Dispatched Simply. Ugh.