JavaScript radio linkage effect

<script>
function checkradio(o,x){
("inptB")[x-1].checked=
}
</script>
<input name="inptA" type="radio" onclick="checkradio(this,1)">aaa
<input name="inptA" type="radio" onclick="checkradio(this,2)">bbb
<input name="inptA" type="radio" onclick="checkradio(this,3)">ccc
<br>
<input name="inptB" type="radio" >111
<input name="inptB" type="radio" >222
<input name="inptB" type="radio" >333