javascript - node.js - how to make a simple live page update?

Question

I'm very very new to node.js, but there's actually only one simple thing that I am trying to achieve by learning the language.

I'd like to create a webpage, where by the code in a specific "div" can be hotswapped on the fly to users currently looking at that page. (ie. the div contains some text, but then an image replaces it.) Ideally, the swap would be executed manually by the the webpage's admin through the click of a button, or some code fired off on the server or something. Regular viewers to the webpage would not be able to do this - they only see the live changes on the page.

real-life example:

live internet broadcast is off-air, therefore the "div" contains "off-air" text. live hotswap of code happens when broadcast goes on-air, and the viewers of the webpage now see the html5 broadcast player in the "div" instead.

What's the simplest way to go about doing this for a node.js newbie?

Many thanks :)

Answer 1

Take a look at Socket.IO http://socket.io/#how-to-use

when the server decides to broadcast a change use:

io.sockets.emit('update-msg', { data: 'this is the data'});

on the client first connect socket.io and then wait for the "update-msg" event and update your dom:

var socket = io.connect('http://localhost');
socket.on('update-msg', function (msg) {
    console.log(msg);
    $('#mydiv').html(msg.data)
});