Try below.

var wsOptions4 = 'BR,SF,GI';
var splitis=wsOptions4.split(',');
 var identifer = g_form.getValue('current_shift_identifier');
for(var i=0;i<splitis.length;i++){
 if (identifer.substring(0,2)==splitis[i]) {
 g_form.setVisible('test',true);//true,false to show/hide
 }
}