Wow--- buenisimo...
Me quede encantado con localStorage...
Código HTML:
Ver original<!DOCTYPE html>
<script type="text/javascript"> function apertura(){
var textarea = document.getElementById("asd");
textarea.focus();
textarea.addEventListener('keyup', function(){
window.localStorage['value'] = textarea.value;
window.localStorage['timestamp'] = (new Date()).getTime();
}, false);
textarea.value = window.localStorage['value'] + window.localStorage['timestamp'];
}
<body onload="apertura();">