Right now we use codemirror's JavaScript mode on the website but there's a JSX mode now so we should start using that instead.

return function() {
      var cm = cm1 || this, withOp = !cm.curOp;
      if (withOp) startOperation(cm);
      try { var result = f.apply(cm, arguments); }
      finally { if (withOp) endOperation(cm); }
      return result;
    };
  }
  function docOperation(f) {