Javascript snippet for comments in the Matasano/Square CTF disassembler

gistfile1.js

/*
  Running this javascript snippet on https://microcorruption.com/cpu/debugger
  will allow you to add comments to the Disassembly window. It also backs up
  every 10 seconds to local storage and will restore if a backup exists when
  first run.
  
  Needs to be run manually on pageload (paste into chrome console) and doesn't
  preserve existing breakpoint highlights (so do it before setting them).
  Will also wipe out the current PC highlight but this will return next step.
  
  I found it particularly helpful for Chernobyl.
  
  - @Sebbity
*/
(function(){
var a = document.getElementById('asmbox');
a.contentEditable=true;
a.onkeydown = function(e) {
  if (e.keyCode == 9) {
    var range,sel = window.getSelection();
    if (sel.rangeCount) {
      range = sel.getRangeAt(0);
      range.insertNode(document.createTextNode('\t'));
      range.collapse(false);
      sel.removeAllRanges();
      sel.addRange(range);
      e.preventDefault();
    }
  }
};
cpu.get("/whoami", function(t) {
  var level = t.level;
  var asmBackup = level + '_backup_asmbox';

  if (localStorage[asmBackup]) {
    a.innerHTML = localStorage[asmBackup];
  };
  window.setInterval(function() {
    console.log(level);
    var asm = document.getElementById('asmbox').cloneNode(true);
    var instructions = asm.getElementsByClassName('insn');
    for (i in instructions) {
      if (instructions[i] && instructions[i].removeAttribute) {
        instructions[i].removeAttribute('style');
      }
    }
    localStorage[asmBackup] = asm.innerHTML;
  }, 10 * 1000);
});
})(this);

Very cool!