Papertrail JSON formatter (with addStyle fix)

userscript.js

// ==UserScript==
// @name        Papertrail JSON formatter
// @namespace   https://papertrailapp.com/
// @version     0.1
// @description Format and colorize JSON log messages in Papertrail
// @match       https://papertrailapp.com/*events*
// @copyright   2014+, Papertrail (http://wiki.creativecommons.org/Public_domain)
// @grant       GM_addStyle
// ==/UserScript==

GM_addStyle(".string { color: #6c71c4; } .number { color: #2aa198; } .boolean { color: #859900; } .null { color: #586e75; } .key { color: #d33682; }");

function syntaxHighlight(json) {
  json = json.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
  return json.replace(/("(\\u[a-zA-Z0-9]{4}|\\[^u]|[^\\"])*"(\s*:)?|\b(true|false|null)\b|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?)/g, function (match) {
    var cls = 'number';
    if (/^"/.test(match)) {
      if (/:$/.test(match)) {
        cls = 'key';
      } else {
        cls = 'string';
      }
    } else if (/true|false/.test(match)) {
      cls = 'boolean';
    } else if (/null/.test(match)) {
      cls = 'null';
    }

    return '<span class="' + cls + '">' + match + '</span>';
  });
}

$('ul#event_list').on('papertrail:loaded', function() {
  $('span.message').each(function(m) {
    console.log("Parsing: " + $(this).text());
    if ($(this).text().substring(0, 1) != '{') {
      return;
    }
    try {
      var formattedString = JSON.stringify(jQuery.parseJSON($(this).text()), undefined, 4);
    } catch(err) {
      return;
    }
    console.log(formattedString);
    formattedString = syntaxHighlight(formattedString);
    formattedString = formattedString.replace(/^{+/g, '').replace(/}+$/g, '');
    formatted = document.createElement('pre');
    formatted = formattedString.replace(/\n    /mg, "\n              ");
    console.log(formattedString);
    formatted.innerHTML = formattedString;
    $(this).html(formatted);
  });
});

Updated version for 2020:

// ==UserScript==
// @name        Papertrail JSON formatter
// @namespace   https://papertrailapp.com/
// @version     0.1
// @description Format and colorize JSON log messages in Papertrail
// @match       https://my.papertrailapp.com/*events*
// @copyright   2014+, Papertrail (http://wiki.creativecommons.org/Public_domain)
// @grant       GM_addStyle
// @require     https://code.jquery.com/jquery-2.2.4.min.js
// ==/UserScript==

GM_addStyle(".string { color: #6c71c4; } .number { color: #2aa198; } .boolean { color: #859900; } .null { color: #586e75; } .key { color: #d33682; }");

function syntaxHighlight(json) {
  json = json.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
  return json.replace(/("(\\u[a-zA-Z0-9]{4}|\\[^u]|[^\\"])*"(\s*:)?|\b(true|false|null)\b|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?)/g, function (match) {
    var cls = 'number';
    if (/^"/.test(match)) {
      if (/:$/.test(match)) {
        cls = 'key';
      } else {
        cls = 'string';
      }
    } else if (/true|false/.test(match)) {
      cls = 'boolean';
    } else if (/null/.test(match)) {
      cls = 'null';
    }

    return '<span class="' + cls + '">' + match + '</span>';
  });
}

setInterval(() => {
  $('.event-list span.message:not(.binded)').click(function () {
      if (!$(this).hasClass('binded')) {
          $(this).addClass('binded')
          console.log("Parsing: " + $(this).text());
          if ($(this).text().substring(0, 1) != '{') {
              return;
          }
          try {
              var formattedString = JSON.stringify(jQuery.parseJSON($(this).text()), undefined, 4);
          } catch(err) {
              return;
          }
          console.log(formattedString);
          formattedString = syntaxHighlight(formattedString);
          // formattedString = formattedString.replace(/^{+/g, '').replace(/}+$/g, '');
          formatted = document.createElement('pre');
          formatted = formattedString.replace(/\n    /mg, "\n              ");
          console.log(formattedString);
          formatted.innerHTML = formattedString;

          $(this).html(formatted);
      }
  })
}, 1000)