Christian Heilmann

Posts Tagged ‘downloadable articles’

A quick idea: JavaScript version controlling for static HTML documents

Monday, January 14th, 2008

When you write tutorials and you want people to use them wherever they are it is a good idea to offer the HTML documents as a zip for downloading. The benefit to the end user is that they don’t need to be online to look something up (I for example have the HTML 4.01 documents on my machine as HTML documents). The drawback is that the documents could be outdated without the user knowing – even when they are online while watching them.

Now, I pondered a bit about this and wondered if something like this wouldn’t be a solution:

  • You add a version number to the title of each document.
  • You add a remotely hosted versions.js script at the end of each document.
  • This script has a JSON object with the version information of each document and compares the file name and version.
  • If the version is outdated, it generates an error message that gets shown to the user.

You can try it out by downloading the two demo documents un-zip them and open them on a computer that is connected to the internet. The second document linked from the first one should be outdated.

The source of versions.js

(checkversion = function(){
// change as fit
var versions = {
var errorID = ‘versionerror’;
var errorMessage = ‘This document is outdated, please go to the homepage to download the new version!’;

// checking code
var d = document;
// get the version number
var cv = d.title.match(/(version (.*))$/);
// get the file name
var cn = window.location.href.split(‘/’);
cn = cn[cn.length-1].split(‘#’)[0];
// check and create error message if there is a mismatch
if(cv[1] && versions[cn]){
if(versions[cn] !== cv[1]){
var m = d.createElement(‘div’); = errorID;



You could create both the titles and the JSON object in versions.js on the backend automatically by scanning the titles or from a version control system. What do you think?