DETERMINING JAVASCRIPT VERSION SUPPORTED

How to determine what version of javascript supported

Example code for Determining javascript version supported:
<script language="javascript">
   version=1.0;
</script>


<script language="JavaScript1.2">
   version=1.2;
</script>

<script language="javascript">
   if(version=1.2)
   {
   
   
   }else{
      
   }
</script>