Slavok47,
<!DOCTYPE HTML>
<html>
<head> </head>
<body>
<input type="radio" name="r1" id="r1" class="r1"><label for="r1">#-1</label><br>
<input type="radio" name="r1" id="r2" class="r1"><label for="r2">#-2</label><br>
<input type="radio" name="r1" id="r3" class="r1"><label for="r3">#-3</label><br>
<input type="radio" name="r1" id="r4" class="r1"><label for="r4">#-4</label><br>
<textarea id="txt" style="display:none;">1</textarea>
<textarea id="txt2" style="display:none;">4</textarea>
<script>
var inp = document.getElementsByClassName('r1');
var txt = document.getElementById('txt');
var txt2 = document.getElementById('txt2');
function func (elm) {
if (elm.id == "r1" && elm.checked)
txt.style.display = "block";
else
txt.style.display = "none";
if (elm.id == "r4" && elm.checked)
txt2.style.display = "block";
else
txt2.style.display = "none";
}
for (var i=0;i<inp.length;i++){
inp[i].onchange = function () {func(this)};
}
</script>
</body>
</html>