Add some color to quotes in pipermail archives

pipermail.js

// ==UserScript==
// @name         Pipermail color!
// @namespace    http://chivil.com/
// @version      0.1
// @description  Colorize quoted text in pipermail
// @author       Romuald Brunet
// @match        http://*/pipermail/*.html
// @match        https://*/pipermail/*.html
// @grant        none
// ==/UserScript==
/* jshint -W097 */
'use strict';


function main(){
  var colors = ['green', 'blue', 'orange', 'red'];
  if (! document.querySelectorAll) { return; }
    
  var elements = document.querySelectorAll('pre > i'),
      l = elements.length;
  for (var i =0; i < l; i++) {
      var element = elements[i];
      var prev = element.previousSibling;
      var content = prev.textContent;
      var match = /(>+)$/.exec(content);
      if (!match) { return; }
      
      var len = match[1].length;
      var index = len - 1;
            
      var parent = element.parentNode;
      
      var color = colors[index % colors.length];
      
      // Previous "paragraph", up to > (not colored)
      var part1 = prev.cloneNode();
      part1.textContent = content.substring(0, content.length - len);

      // The ">" part (colored)
      var part2 = document.createElement("span");
      part2.textContent = match[1];
      part2.setAttribute('style', "color: " + color);

      parent.replaceChild(part2, prev);
      parent.insertBefore(part1, part2);

      element.setAttribute('style', "color: " + color);
  }
}

main();