ChromeDebugger.js

var script = document.createElement("script");
script.setAttribute("src", "http://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js");
script.addEventListener('load', function() {
  var script = document.createElement("script");
  document.body.appendChild(script);
}, false);
document.body.appendChild(script);

ChromeDebugger_v2.js

// For quickly trying things out in the browser, jQuery and Lo-Dash (like Underscore.js) are great.
// Read the code below (never copy & paste code you don't trust),
// then you can copy & paste it into the browser console to load jQuery & lodash.

(function () {
  var jq = document.createElement('script');
  jq.src = 'https://code.jquery.com/jquery-2.1.4.js';
  document.getElementsByTagName('head')[0].appendChild(jq);
  // jQuery should be available via "jQuery" (and we'll set up the $ alias in the defer() function)

  var ld = document.createElement('script');
  ld.src = 'https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.1/lodash.js';
  document.getElementsByTagName('head')[0].appendChild(ld);
  // lodash should be available via "_".

  var defer = function () {
    if (window.jQuery) {
      jQuery.noConflict();
      $ = jQuery;
      // jQuery should be available via "$".
    } else {
      setTimeout(function () {
        defer();
      }, 50);
    }
  };
  defer(); // wait for jQuery to download, then set up $ alias

  console.log('jQuery ($) and lodash (_) should now be available in your browser console.');
  console.log('If not, there may be a Content Security Policy error.');
  console.log('See: https://jquery.com https://lodash.com for documentation.')

}());