How can this be modified so that the selection in font size will be maintained?

var fontSize = 8;

function FontSizeSet()
{
var el, n = 1;
while (el = document.getElementById('pagetext' + n++))
el.style.fontSize = fontSize + 'pt';
return false;
}

function SetFontLarger()
{
if (fontSize < 12)
fontSize++;
return FontSizeSet();
}

function SetFontSmaller()
{
if (fontSize > 7)
fontSize--;
return FontSizeSet();
}