I just want to Get hello in Label1
<script type="text/javascript">
result = "helloworld"
document.getElementById('<%= Label1.ClientID %>').innerHTML = result;
</script>
have you tried doing result.substring(0,5);
<script type="text/javascript">
result = "helloworld"
document.getElementById('<%= Label1.ClientID %>').innerHTML = result.substring(0,5);
</script>