Persistence

• INI files
• XML
• Cookies are small but can still slow processing
• userData 64k
• Local Shared Objects (Flash)

HTML5 Storage

• supported by all major browsers
• to check:

  function supports_html5_storage() {
  try {
    return 'localStorage' in window && window['localStorage'] !== null;
  } catch (e) {
    return false;
  }
  }
  

• based on key value pairs
• treatted as assoc. array

var foo = localStorage.getItem("bar");
// ...
localStorage.setItem("bar", foo);

• or just use bracket notation

var foo = localStorage["bar"];
// ...
localStorage["bar"] = foo;

• to iterate through all keys

interface Storage {
  readonly attribute unsigned long length;
  getter DOMString key(in unsigned long index);
};

If you call key() with an index that is not between 0–(length-1), the function will return null.

if (window.addEventListener) {
  window.addEventListener("storage", handle_storage, false);
} else {
  window.attachEvent("onstorage", handle_storage);
};

Therefore, to hook the storage event, you’ll need to check which event mechanism the browser supports.

function handle_storage(e) {
  if (!e) { e = window.event; }
}

• storage event object

  function saveGameState() {
    if (!supportsLocalStorage()) { return false; }
    localStorage["halma.game.in.progress"] = gGameInProgress;
    for (var i = 0; i < kNumPieces; i++) {
    localStorage["halma.piece." + i + ".row"] = gPieces[i].row;
    localStorage["halma.piece." + i + ".column"] = gPieces[i].column;
    }
    localStorage["halma.selectedpiece"] = gSelectedPieceIndex;
    localStorage["halma.selectedpiecehasmoved"] = gSelectedPieceHasMoved;
    localStorage["halma.movecount"] = gMoveCount;
    return true;
  }