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.

cm.curOp = {
      
      
      changes: [],
      forceUpdate: false,
      updateInput: null,
      userSelChange: null,
      textChanged: null,
      selectionChanged: false,
      cursorActivity: false,
      updateMaxLine: false,
      updateScrollPos: false,
      id: ++nextOpId
    };
    if (!delayedCallbackDepth++) delayedCallbacks = [];
  }
  function endOperation(cm) {