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.

killLine: function(cm) {
      var from = cm.getCursor(true), to = cm.getCursor(false), sel = !posEq(from, to);
      if (!sel && cm.getLine(from.line).length == from.ch)
        cm.replaceRange("", from, Pos(from.line + 1, 0), "+delete");
      else cm.replaceRange("", from, sel ? to : Pos(from.line), "+delete");
    },
    deleteLine: function(cm) {
      var l = cm.getCursor().line;
      cm.replaceRange("", Pos(l, 0), Pos(l), "+delete");
    },
    delLineLeft: function(cm) {
      var cur = cm.getCursor();
      cm.replaceRange("", Pos(cur.line, 0), cur, "+delete");
    },
    undo: function(cm) {cm.undo();},
    redo: function(cm) {cm.redo();},
    goDocStart: function(cm) {cm.extendSelection(Pos(cm.firstLine(), 0));},
    goDocEnd: function(cm) {cm.extendSelection(Pos(cm.lastLine()));},
    goLineStart: function(cm) {
      cm.extendSelection(lineStart(cm, cm.getCursor().line));
    },
    goLineStartSmart: function(cm) {
      var cur = cm.getCursor(), start = lineStart(cm, cur.line);
      var line = cm.getLineHandle(start.line);
      var order = getOrder(line);
      if (!order || order[0].level == 0) {
        var firstNonWS = Math.max(0, line.text.search(/\S/));
        var inWS = cur.line == start.line && cur.ch <= firstNonWS && cur.ch;
        cm.extendSelection(Pos(start.line, inWS ? 0 : firstNonWS));
      } else cm.extendSelection(start);