pashin76,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script>
window.onload = function () {
function d() {
if (a.scrollTop < a.scrollHeight - a.clientHeight) a.scrollTop += 4, requestAnimationFrame(d); // a.scrollTop = a.scrollHeight - a.clientHeight перемещение сразу
else {
var b = a.value.length;
if (a.setSelectionRange) a.setSelectionRange(b, b);
else if (a.createTextRange) {
var c = a.createTextRange();
c.collapse(!0);
c.moveEnd("character", b);
c.moveStart("character", b);
c.select()
}
a.focus()
}
}
var a = document.querySelector("#text");
a.value += Array(20).join("qwerty\n");
a.onpaste = d;
d()
};
</script>
</head>
<body>
<textarea id="text" name="text" cols="20" rows="5"></textarea>
</body>
</html>