Bookmarklet that allows me to add a link to more information for specific emails I receive

README.md

I receive a number of periodic emails that prompt me to do something (e.g. take an electricity meter reading). I wanted to be able to add information to those emails to remind me how to perform the task.

This JavaScript allows me to configure rules so that I can display a link to a web page when I'm viewing an email with a specific subject in Gmail.

I'm currently hosting the JavaScript and installer web page using rawgit.com.

Visit this page to install the bookmarklet.

bookmarklet.js

// Original
(function() {
  var script = document.createElement('script');
  script.src = 'https://rawgit.com/chrisroos/8840a1d9c506236b57fb/raw/5cd978e1b01aee2c58fd6ffbfeabc61fb55b410d/gmail-rules.js';
  document.body.appendChild(script);
})();

// One line (done by hand)
(function(){ var script = document.createElement('script'); script.src = 'https://rawgit.com/chrisroos/8840a1d9c506236b57fb/raw/5cd978e1b01aee2c58fd6ffbfeabc61fb55b410d/gmail-rules.js'; document.body.appendChild(script); })();

gmail-rules.js

var rules = [
  {
    subject: /Reminder to file your VAT Return/,
    url: 'https://github.com/freerange/business/wiki/Reminder-to-file-your-VAT-Return:-Email-from-HMRC'
  }
];

var matchEmails = function($) {
  // The subject appears in an h2 in Gmail web interface
  $('h2').each(function(index, element) {
    $(rules).each(function(index, rule) {
      if ($(element).text().match(rule.subject)) {
        var link = $('<a>');
        link.attr('href', rule.url);
        link.text('More information');
        $(element).append(' - ');
        $(element).append(link);
      };
    });
  });
};

var jQueryAvailable = function() {
  return (typeof(jQuery) != 'undefined');
};

if (!jQueryAvailable()) {
  var script = document.createElement('script');
  script.src = 'https://code.jquery.com/jquery-2.1.3.min.js';
  document.body.appendChild(script);
};

// Wait for jQuery before calling matchEmails()
var pid = setInterval(function() {
  if (jQueryAvailable) {
    matchEmails(jQuery);
    clearInterval(pid);
  }
}, 1000);

index.html

<a href="javascript:(function(){ var script = document.createElement('script'); script.src = 'https://rawgit.com/chrisroos/8840a1d9c506236b57fb/raw/5cd978e1b01aee2c58fd6ffbfeabc61fb55b410d/gmail-rules.js'; document.body.appendChild(script); })();">Gmail rules</a>