task
Essentially, count the number of occurrences of =={{header| on each task page.

Output:

100 doors: 20 examples.
99 Bottles of Beer: 29 examples.
Abstract type: 10 examples.

Total: X examples.
For a full output, updated periodically, see Rosetta Code/Count examples/Full list.

You'll need to use the Media Wiki API, which you can find out about locally, here, or in Media Wiki's API documentation at, API:Query

var lwp = require('LWP::UserAgent').new(agent => 'Mozilla/5.0');
 
var site = 'http://rosettacode.org';
var list_url = '/mw/api.php?action=query&list=categorymembers&'+
               'cmtitle=Category:Programming_Tasks&cmlimit=500&format=xml';
 
var content = lwp.get(site + list_url).decoded_content;
 
while (var m = content.match(/cm.*?title="(.*?)"/g)) {
    (var slug = m[0]).gsub!(' ', '_');
    var count = lwp.get("#{site}/wiki/#{slug}").decoded_content.count(/toclevel-1/g);
    say "#{m[0]}: #{count} examples";
}