Try

ClientMethod changeParams() [ Language = javascript ]
{
  var query zen('categorieBeneficiaire');
  var param1 zen('catBParam1');
  var param2 zen('catBParam2');

  param1.value='OS';
  param2.value='NSAL';
  query.refreshContents();
}

/// This client event, if present, is fired when the page is loaded.
ClientMethod onloadHandler() [ Language = javascript ]
{
  zenPage.changeParams();
}

Another variants:

USER>k  s args=3,args(1)="-h",args(2)=21,args(3)="community.intersystems.com" do $system.OBJ.DisplayError(##class(%Net.Remote.Utility).RunCommandViaCPIPE("tracert",,.output,,900,.args)) output

or

USER>k  s args=3,args(1)="-h",args(2)=21,args(3)="community.intersystems.com" do $system.OBJ.DisplayError(##class(%Net.Remote.Utility).RunCommandViaZF("tracert",,.output,,900,,.args)) output

See Handling of static dataEN or Обработка статикиRU.

In your case, is enough will be the standard class %CSP.StreamServer (see streamserve.csp from CSP Samples).
And you can use it to download external files, for example: %25CSP.StreamServer.cls?FILE=blablabla

PS: by the way, it is not safe to transmit OID in open form, so pay attention to the method %CSP.Page:Encrypt(oid).

Changed a bit and added new code:

/// d ##class(Scratch.test).ClassVsInst()
ClassMethod ClassVsInst(= {1e6}) [ ProcedureBlock = 0, PublicList = st ]
{
   p1p2p3p4p5p6p7p8p9p10xClassxInstst
   
   p1="пропоывшыщзшвыщшв"
    ,p2="гшщыгвыовлдыовдьыовдлоыдлв"
    ,p3="widuiowudoiwudoiwudoiwud"
    ,p4="прпроыпворыпворыпворыпв"
    ,p5="uywyiusywisywzxbabzjhagjЭ"
    ,p6="пропоывшыщзшвыщшв"
    ,p7="гшщыгвыовлдыовдьыовдлоыдлв"
    ,p8="widuiowudoiwudoiwudoiwud"
    ,p9="прпроыпворыпворыпворыпв"
    ,p10="uywyiusywisywzxbabzjhagjЭ"
    
    ,xClass="(args...) f i=1:1:N s sc=##class(Scratch.test).%1(args...)"
    ,xInst="(args...) f i=1:1:N s sc=st.%1(args...)"
   
   
   st=##class(Scratch.test).%New()
   
   w $p($zv,"(Build"),!!
   
   runClassmethod("dummyClass10"p1p2p3p4p5p6p7p8p9p10)
    ,runMethod("dummyClass10"p1p2p3p4p5p6p7p8p9p10)
    ,runMethod("dummyInst10"p1p2p3p4p5p6p7p8p9p10)
    ,runClassmethod("dummyClass5"p1p2p3p4p5)
    ,runMethod("dummyClass5"p1p2p3p4p5)
    ,runMethod("dummyInst5"p1p2p3p4p5)
    ,runClassmethod("dummyClassNull")
    ,runMethod("dummyClassNull")
    ,runMethod("dummyInstNull")
   
    ,runX("dummyClass10",xClassp1p2p3p4p5p6p7p8p9p10)
    ,runX("dummyInst10",xInstp1p2p3p4p5p6p7p8p9p10)
    ,runX("dummyClass5",xClassp1p2p3p4p5)
    ,runX("dummyInst5",xInstp1p2p3p4p5)
    ,runX("dummyClassNull",xClass)
    ,runX("dummyInstNull",xInst)
  
runMethod(methodname,args...)
   t,i,sc
   t=$zh f i=1:1:sc=$method(stmethodnameargs...)
   t=$zh-methodname,?16,"total time = "_t,?38,"avg time = "_(t/N),!
   q
runClassmethod(methodname,args...)
   t,i,sc
   t=$zh f i=1:1:sc=$classmethod("Scratch.test"methodnameargs...)
   t=$zh-methodname_"*",?16,"total time = "_t,?38,"avg time = "_(t/N),!
   q
runX(methodname,x,args...)
   t,i,sc
   t=$zh
   x ($$$FormatText(x,methodname), args...)
   t=$zh-"X"_methodname,?16,"total time = "_t,?38,"avg time = "_(t/N),!
   q
}
Result:

USER>##class(Scratch.test).ClassVsInst()
Cache for Windows (x86-64) 2018.1
 
dummyClass10*   total time = .328227  avg time = .000000328227
dummyClass10    total time = .27655   avg time = .00000027655
dummyInst10     total time = .259913  avg time = .000000259913
dummyClass5*    total time = .286983  avg time = .000000286983
dummyClass5     total time = .25666   avg time = .00000025666
dummyInst5      total time = .240312  avg time = .000000240312
dummyClassNull* total time = .274406  avg time = .000000274406
dummyClassNull  total time = .250926  avg time = .000000250926
dummyInstNull   total time = .234486  avg time = .000000234486
XdummyClass10   total time = .312917  avg time = .000000312917
XdummyInst10    total time = .264871  avg time = .000000264871
XdummyClass5    total time = .286985  avg time = .000000286985
XdummyInst5     total time = .238557  avg time = .000000238557
XdummyClassNull total time = .278684  avg time = .000000278684
XdummyInstNull  total time = .236815  avg time = .000000236815

I have a few comments.:

  1. your code finds by the class name, not the table name, which is confusing

    For example, for the next class, the method finds nothing:

    Class dc.test Extends %Persistent SqlTableName aaa ]
    {
    ...
    }

    USER>##class(objectscript.findTable).test("aaa")
    ?
  2. according to the documentation, your code uses the deprecated API:
    proof
    The Caché Library set of class definitions classes has been superseded by the %Dictionary package. The %Library classes described here are maintained for compatibility with existing applications.

    New code should make use of the classes within the %Dictionary package.

  3. in fact, the search is done elementary:

    select ClassName from %Dictionary.ClassDefinition_ClassIndex() where ClassName 'test'

    or

    select ClassName from %Dictionary.ClassDefinition_ClassIndex() where nvl(SqlTableName,ClassName) [ 'aaa'

Can also speed up, abandoning the indirect:

  s:'$d(addr3addr3(1)=1, (addr3(2),addr3(8),addr3(9))=289, addr3(3)=3
  
  d $case(addr3(value),1:t3case1,289:t3case289,3:t3case3,:t3case)
  ##; w !,r
  q  

t3case1
  r="Case 1"
  q
t3case289
  r="Case 2,8-9" q
t3case3
  r="Case 3"
  q
t3case
  r"Case default"
  q

But the quickest option is if/elseif/else, since here is used inline-call, and not external-call.