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.

}, true);
  option("coverGutterNextToScrollbar", false, updateScrollbars, true);
  option("lineNumbers", false, function(cm) {
    setGuttersForLineNumbers(cm.options);
    guttersChanged(cm);
  }, true);
  option("firstLineNumber", 1, guttersChanged, true);
  option("lineNumberFormatter", function(integer) {return integer;}, guttersChanged, true);
  option("showCursorWhenSelecting", false, updateSelection, true);
  option("resetSelectionOnContextMenu", true);
  option("readOnly", false, function(cm, val) {
    if (val == "nocursor") {
      onBlur(cm);
      cm.display.input.blur();
      cm.display.disabled = true;
    } else {
      cm.display.disabled = false;
      if (!val) resetInput(cm, true);
    }
  });
  option("dragDrop", true);
  option("cursorBlinkRate", 530);
  option("cursorScrollMargin", 0);
  option("cursorHeight", 1);
  option("workTime", 100);
  option("workDelay", 100);
  option("flattenSpans", true);
  option("pollInterval", 100);
  option("undoDepth", 40, function(cm, val){cm.doc.history.undoDepth = val;});
  option("historyEventDelay", 500);