stackoverflow_code_block_copy_link.user.js

// ==UserScript==
// @name        StackOverflow Code Block Copy Link 
// @description Shows a copy icon in top right of stackexchange code blocks
// @version     0.1
// @author      RossRogers
// @include     http://stackoverflow.com/*
// @grant       GM_getValue
// @grant       GM_setValue
// @grant       GM_xmlhttpRequest
// @grant       GM_setClipboard
// ==/UserScript==

'use strict';

$( document ).ready(function(){
  $('<style type="text/css">       \n'+
      '.showme-abs {               \n'+
      '  opacity: 0;               \n'+
      '  transition: opacity 700ms;\n'+
      '}                           \n'+
      '.showhim:hover .showme-abs {\n'+
      '  opacity: 1;               \n'+
      '}                           \n'+
      '.clipboard {                \n'+
      '  margin-left: 80%;         \n'+
      '}                           \n'+
    '</style>'
    ).appendTo('head');
  var code_blocks = $('pre code');
  code_blocks.addClass('showhim');
  code_blocks.prepend($(
    '<div class="clipboard showme-abs">'+
      '<a href="javascript:void(0)" class="copy-the-code" title="Click to the code.">Copy</a>'+
    '</div>'));
  
  $('.copy-the-code').on('click', function(event) {
    GM_setClipboard($(event.target).closest('code').text().replace('Copy',''));  
  });
});