Function in JavaScript

<SCRIPT LANGUAGE='JavaScript'>
<!--
    var aString = "A"
    var aNumber = 1;
    function test(aString, aNumber) {
      aString = "B";
      aNumber = 2;
      document.write("<BR><BR><BR><BR><BR>During function call:<BR>");
      document.write("aStringCopy=",aString,"<BR>");
      document.write("aNumberCopy=",aNumber,"<BR>");
    }

    document.write("<BR><BR><BR><BR><BR>Before function call:<BR>");
    document.write("aString=",aString,"<BR>");
    document.write("aNumber=",aNumber,"<BR>");


    test(aString,aNumber);


    document.write("<BR><BR><BR><BR><BR><BR><BR>After function call:<BR>");
    document.write("aString=",aString,"<BR>");
    document.write("aNumber=",aNumber,"<BR>");
    //-->
</SCRIPT>