Function isModifierKey

src/cm/codemirror.js:2224–2227

(event)

    return lookup(map);
  }
  function isModifierKey(event) {
    var name = keyNames[e_prop(event, "keyCode")];
    return name == "Ctrl" || name == "Alt" || name == "Shift" || name == "Mod";
  }
  CodeMirror.isModifierKey = isModifierKey;

  CodeMirror.fromTextArea = function(textarea, options) {