<!DOCTYPE html>
<html>
<body>
<textarea id="testBox" style="padding:2px;" readonly></textarea>
<script type="text/javascript">
//Adding focus to the textbox should trigger a spellcheck
var textbox = document.getElementById("testBox");
addEventListener("load", function() {
textbox.readOnly = false;
textbox.focus();
textbox.value = "blahblahblah";
textbox.selectionStart = textbox.selectionEnd = 0;
textbox.blur();
}, false);
</script>
</body>
</html>