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.

var word = findWordAt(getLine(doc, start.line).text, start);
      extendSelection(cm.doc, word.from, word.to);
    } else { lastClick = {time: now, pos: start}; }
    var last = start;
    if (cm.options.dragDrop && dragAndDrop && !isReadOnly(cm) && !posEq(sel.from, sel.to) &&
        !posLess(start, sel.from) && !posLess(sel.to, start) && type == "single") {
      var dragEnd = operation(cm, function(e2) {
        if (webkit) display.scroller.draggable = false;
        cm.state.draggingText = false;
        off(document, "mouseup", dragEnd);
        off(display.scroller, "drop", dragEnd);
        if (Math.abs(e.clientX - e2.clientX) + Math.abs(e.clientY - e2.clientY) < 10) {
          e_preventDefault(e2);
          extendSelection(cm.doc, start);
          focusInput(cm);
        }
      });
      
      if (webkit) display.scroller.draggable = true;
      cm.state.draggingText = dragEnd;
      
      if (display.scroller.dragDrop) display.scroller.dragDrop();
      on(document, "mouseup", dragEnd);
      on(display.scroller, "drop", dragEnd);
      return;
    }
    e_preventDefault(e);
    if (type == "single") extendSelection(cm.doc, clipPos(doc, start));
    var startstart = sel.from, startend = sel.to, lastPos = start;
    function doSelect(cur) {