KeyboardEvent.getModifierState()

El método KeyboardEvent.getModifierState() retorna true respecto al estado actual de la tecla modificadora especificada si la misma está presionada o bloqueada, en caso contrario devuelve false.

var active = event.getModifierState(keyArg);

A Boolean

keyArg

El valor de la tecla modificadora. El valor debe ser uno de los valores KeyboardEvent.key que representan las teclas modificadoras, o el string "Accel" , el cual es case-sensitive.

IE9 usa "Scroll" para "ScrollLock" y "Win" para "OS".

• On the other platforms, "Alt", "Control" and "Shift" may be supported.
• All modifiers (except "FnLock", "Hyper", "Super" and "Symbol" which are defined after Gecko implements this) are always supported for untrusted events on Gecko. This doesn't depend on the platform.

getModifierState() also accepts a deprecated virtual modifier named "Accel". event.getModifierState("Accel") returns true when at least one of KeyboardEvent.ctrlKey (en-US) or KeyboardEvent.metaKey is true.

In old implementations and outdated specifications, it returned true when a modifier which is the typical modifier key for the shortcut key is pressed. For example, on Windows, pressing Ctrl key may make it return true. However, on Mac, pressing ⌘ Command key may make it return true. Note that which modifier key makes it return true depends on platforms, browsers, and user settings. For example, Firefox users can customize this with a pref, "ui.key.accelKey".

// Ignore if following modifier is active.
if (event.getModifierState("Fn") ||
    event.getModifierState("Hyper") ||
    event.getModifierState("OS") ||
    event.getModifierState("Super") ||
    event.getModifierState("Win") /* hack for IE */) {
  return;
}

// Also ignore if two or more modifiers except Shift are active.
if (event.getModifierState("Control") +
    event.getModifierState("Alt") +
    event.getModifierState("Meta") > 1) {
  return;
}

// Handle shortcut key with standard modifier
if (event.getModifierState("Accel")) {
  switch (event.key.toLowerCase()) {
    case "c":
      if (event.getModifierState("Shift")) {
        // Handle Accel + Shift + C
        event.preventDefault(); // consume the key event
      }
      break;
    case "k":
      if (!event.getModifierState("Shift")) {
        // Handle Accel + K
        event.preventDefault(); // consume the key event
      }
      break;
  }
  return;
}

// Do somethig different for arrow keys if ScrollLock is locked.
if ((event.getModifierState("ScrollLock") ||
       event.getModifierState("Scroll") /* hack for IE */) &&
    !event.getModifierState("Control") &&
    !event.getModifierState("Alt") &&
    !event.getModifierState("Meta")) {
  switch (event.key) {
    case "ArrowDown":
    case "Down": // hack for IE and old Gecko
      event.preventDefault(); // consume the key event
      break;
    case "ArrowLeft":
    case "Left": // hack for IE and old Gecko
      // Do something different if ScrollLock is locked.
      event.preventDefault(); // consume the key event
      break;
    case "ArrowRight":
    case "Right": // hack for IE and old Gecko
      // Do something different if ScrollLock is locked.
      event.preventDefault(); // consume the key event
      break;
    case "ArrowUp":
    case "Up": // hack for IE and old Gecko
      // Do something different if ScrollLock is locked.
      event.preventDefault(); // consume the key event
      break;
  }
}

• The KeyboardEvent this method belongs to.
• MouseEvent.getModifierState (en-US)