The parameter order should not normally matter but if it does just revise the javascript as follows

my $JSCRIPT=<<EOF;
  function clickme(){
    var URL = 'http://a.com:8080/bms/healthMonitor.do?method=redirect'
    + '&operation=BackupHistorySearch'
    + '&subOperation=GetReport'
    + '&clientName=' + document.getElementById("ta").value
    + '&fromDateStr=$FM&toDateStr=$TM'
    // comment out if or remove when working OK
    if (confirm(URL)==true) { 
      window.open(URL)
    };
  }
EOF
[download]

poj