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shared server+client rendering with live updates for key/value stores

why progressive enhancement is great

  • no more staring at a blank page for your javascript to load plus another round-trip for the content to load
  • accessible by default
  • search engine friendly
  • inspect your markup with curl


Given some simple html:

<div class="message">
    <span class="who"></span>
    <span class="time"></span>
  <div class="body"></div>

we can write some simple rendering logic that will work on both the server and the browser (with browserify and brfs):

var hyperkey = require('hyperkey');
var fs = require('fs');
var html = fs.readFileSync(__dirname + '/message.html');
module.exports = function () {
    return hyperkey(html, function (row) {
        return {
            '.time': row.time,
            '.who': row.who,
            '.body': row.body

To hook up a live stream from the server to the rendering logic in the browser, we can just do:

var shoe = require('shoe');
var render = require('./render/message.js')();
var sock = shoe('/sock');

The render instance will output data to the websocket to keep track of the keys and ranges to track updates automatically.

Now all we need is a server to pipe our rendering logic into some html:

var http = require('http');
var ecstatic = require('ecstatic')(__dirname + '/static');
var trumpet = require('trumpet');
var fs = require('fs');
var sub = require('level-sublevel');
var level = require('level');
var db = sub(level('test.db', { valueEncoding: 'json' }));
var tracker = require('level-track')(db);
var render = require('./render/message.js');
var server = http.createServer(function (req, res) {
    if (req.url === '/') {
        var tr = trumpet();
        var range = [ 'message', 'message~' ];
        var messages ='#messages');
        messages.setAttribute('data-start', range[0]);
        messages.setAttribute('data-end', range[1]);
        db.createReadStream({ start: range[0], end: range[1] })
    else ecstatic(req, res);
var shoe = require('shoe');
var sock = shoe(function (stream) {
sock.install(server, '/sock');
function readStream (file) {
    return fs.createReadStream(__dirname + '/static/' + file);

The server will render all the messages written to the database into the html and then whenever more data is written to the db, the browser will update automatically!


var hyperkey = require('hyperkey')

var stream = hyperkey(html, cb)

Create an object stream from an html string html and a callback cb(value, key).

When an object is written to the stream, cb(value, key) fires with the row.value and the row.key.

The cb(value, key) should return an object mapping css selectors to attributes and content as described by hyperspace.

On the server, the stream will output html data that can be piped to the response object in an http handler.

In the browser, the stream will output newline-delimited json that can be fed into level-track to automatically track the rendered ranges on the page to subscribe to live updates.

stream.{appendTo,prependTo,sortTo}(target, ...)

In the browser, you can call methods on the underlying hyperspace instance to insert elements into the DOM.


With npm do:

npm install hyperkey