Change Button label

How to change button label? Like if the Lock status is locked change the button label to Unlock and vice versa.Please help

var text lockStatus=If([Lock Status]="LOCKED","UNLOCKED","LOCKED");
var text URLONE=URLRoot()&"/db/"&Dbid()&"?act=API_EditRecord&rid=" &[Record ID#] & "&_fid_9="&$lockStatus;
var text URLTWO=URLRoot() & "db/" & Dbid()&"?a=dr&rid="&[Record ID#];
$URLONE
& "&rdr=" & URLEncode($URLTWO)

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Ronali Panigrahy
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