Zerver is a lightweight Node.js-based webserver that lets you seamlessly make server API calls as if they were a library on the client. The goal is to provide a developer-focused toolset and remove all the boilerplate involved in serving a webapp.

Install

npm install -g zerver
# or add zerver to your package.json dependencies

Basic usage

Let's say you have a directory of this structure.

website-dir/index.html
website-dir/zerver/MyAPI.js

Everything in website-dir will be served as static content except for code in zerver/ which will run on the server.

// in website-dir/zerver/MyAPI.js
// this runs on the server
exports.logStuff = function (str) {
    console.log(str); // 'hi from client'
    callback('hi from server');
};

<!-- in website-dir/index.html -->
<!-- this runs in the browser -->
<script src="zerver/MyAPI.js"></script>
<script>
    MyAPI.logStuff('hi from client', function (str) {
        console.log(str); // "hi from server"
    });
</script>

# run the server
zerver website-dir
# go to http://localhost:8888/ to view the magic

What just happened?

MyAPI.logStuff automatically serializes the arguments of the function call and makes an AJAX request to the server. The server runs the function in website-dir/zerver/MyAPI.js and responds to the client in a similar way.

Any amount of arguments can be used in the function calls as long as they are JSON stringify-able (with the exception of the callback function).

Note: any server code in a subdirectory of website-dir/zerver will not be available for import on the client allowing for libraries of private server functionality.

Require syntax

<!-- in website-dir/index.html -->
<script src="/zerver/require.js"></script>
<script>
    var MyAPI = require('MyAPI');
    MyAPI.logStuff('hi from client', function (str) {
        console.log(str); // "hi from server"
    });
</script>

Tools

Debug mode

zerver -d website-dir

Zerver will automatically reload the server modules when any server-side code is edited. This is allows for rapid development and testing of server-side code.

Auto-refresh mode

zerver -dr website-dir

Any webpage being viewed that has a Zerver script on it (website-dir/index.html) will automatically refresh when any of its code is edited. You can edit code and immediately see feedback on how it effects your running webapp.

ExpressJS integration

Zerver integrates well with Express, providing the same functionality to any existing webapp.

// "app" is an ExpressJS app instance
var zerver = require('zerver');
app.use( zerver.middleware('path/to/zerver/scripts', 'url/to/zerve/at') );

Along with the rest of your Express app, Zerver scripts will be accessible the specified path (url/to/zerve/at) for importing into your client-side code.

Node module

A convenient tool for testing and server-to-server integration is the NodeJS Zerver module.

var zerver = require('zerver');

zerver.get('http://localhost:8888/zerver/', function (myzerver) {
    myzerver.MyAPI.logStuff('hi from another server', function (str, data) {
        console.log(str); // "hi from server"
    });
});

Advanced usage

Zerver options

# run server on a different port
zerver --port=8000 website-dir

# automatically append a comment timestamp whenever
# a HTML5 cache.manifest is requested
zerver -d --manifest=path/to/cache.manifest website-dir

# in production mode this will always have
# the timestamp of the time of deploy
zerver --manifest=path/to/cache.manifest website-dir

Default options

You can specify default options in an environment variable, to avoid having to type them every time

export ZERVER_FLAGS='-drl'

Cross origin

Zerver can automatically make a script available to multiple host origins. This is especially useful if you are including a Zerver script from a subdomain of your webapp.

// in website-dir/zerver/MyAPI.js

// all any website to include your zerver script
exports._crossOrigin = '*';

The value of exports._crossOrigin is exactly what will be served as the Allow-Access-Control-Origin header for cross origin requests if acceptable.

Script names

Zerver scripts can be globalised on the client under whatever name you please. If you are afraid of object name collisions simply define the query argument name for the script and it will be globalised as such.

<!-- in website-dir/index.html -->
<script src="zerver/MyAPI.js?name=SomeOtherAPI"></script>
<script>
    SomeOtherAPI.logStuff('hi from client', function (str) {
        console.log(str); // "hi from server"
    });
</script>

Error handling

<!-- in website-dir/index.html -->
<script src="zerver/MyAPI.js"></script>
<script>
    MyAPI.logStuff('hi from client', function (str) {
        // this === MyAPI
        console.log(str); // "hi from server"
    }).error(function (err) {
        // this === MyAPI
        console.log(err); // error string explaining failure
    });
</script>

Example apps

Basic app

Express app