Get Cursor Position using Javascript

To Get Cursor staring position using Javascript
function getSelectionStart(o)
{
if (o.createTextRange)
{
var r = document.selection.createRange().duplicate()
r.moveEnd('character', o.value.length)
if (r.text == '') return o.value.length
return o.value.lastIndexOf(r.text)
}
else
return o.selectionStart
}

To Get Cursor End position using Javascript
function getSelectionEnd(o)
{
if (o.createTextRange)
{
var r = document.selection.createRange().duplicate()
r.moveStart('character', -o.value.length)
return r.text.length
}
else
return o.selectionEnd
}