page modified date tracking

[technickle]

Each page should display the date on which it was last modified. This should be determined automatically, ideally from Jekyll/Liquid variables, and injected into the _layouts/default.html template.

[technickle]

Can't identify a built-in variable which might do this. It might be possible to embed a "now" function onto each page in the hopes that only modified pages get regenerated by the jekyll engine during the publishing process.

[aepstein]

Looks like there is a jekyll plugin to support this: jekyll-last-modified-at. Github pages only supports building with plugins they have whitelisted. The gem is not in github-pages, so the only way to use it would be to build the site locally and commit it to the repo. I put a request into github pages to see if they will add this plugin to their (rather short) whitelist (github/pages-gem#119).

[technickle]

Client-side, using jQuery.ajax(...).getResponseHeader('Last-Modified') or

var xhReq = new XMLHttpRequest();
xhReq.open("HEAD", "My_File.xlsx", false);
xhReq.send(null);
var lastModified = xhReq.getResponseHeader("Last-Modified");

would work, except the github pages jekyll engine seems to update all the files in the compiled site, even if they were not modified during the commit.

[technickle]

Perhaps the best method I can find is to make an ajax call to the github API:

> $.ajax({url: "https://api.github.com/repos/technickle/open-data-resources/commits?path=/bills/bills.csv", success: function(data){console.log(data[0].commit.author.date)}})
2015-02-12T17:53:27Z

The response is actually an array of commit objects, and they don't seem to be in date/time order, but that could be addressed pretty easily in-code.

The URL can be parameterized in the frontmatter YML for the relevant page.