JavaScript : Check for Number Input

<script type=”text/javascript”>
//var mikExp = /[$\\@\\\#%\^\&\*\(\)\[\]\+\_\{\}\`\~\=\|]/;
var acceptedInput = /[0123456789]/;

function checkNumber(val)
{
var strPass = val.value;
var strLength = strPass.length;
var lchar = val.value.charAt((strLength) – 1);

if(lchar.search(acceptedInput) == -1)
{
var tst = val.value.substring(0, (strLength) – 1);
val.value = tst;
}
}

</script>