Escape delphi strings to JavaScript function

Question

I need to pass fields content from a table database to a JavaSricpt function in my web page.

I found an error when I have a backslash in the string :

{"DT_RowId":"4427","pront":"4427","nome":"JOHN DOE","conv":"PETROBRAS\ DISTR ( R)","cpf":"","email":""}

See:"PETROBRAS\"

In this case, I found that backslash was the cause of the problem.

I know I can solve this particular problem, but the table database I am using has many rows, and may be, can have others chars that can cause problems to JavaScript in my page

Is there a delphi function to escape all invalids chars(considering JavaScript) in a delphi string in order to pass to jasvascript function?

function EscapeDelphiStringToJS(s:string):string
begin
  result:= "how  could I do the escaping?"
end;

Remy, Here is the code I am using to create the Json. I am using XE8.

In order to return the data to my ajax function, I just convert the result function to string using: jso.tostring; But, this is not the problem.

function TContentClient.select_client(aParams: TStrings): 
var so,jsoItem:TJsonObject;
    jsa:TJsonArray;
    jsp:TJSONPair;
    ds:Tdataset;
  .....
begin
            TJsonObject;_recordsTotal:=IntToStr(ds.RecordCount);
            jso:=TJsonObject.Create;
            jso.AddPair('draw',TJsonNumber.Create(_draw));
            jso.AddPair('recordsTotal',TJsonNumber.Create(_recordsTotal));
            jso.AddPair('recordsFiltered',TJsonNumber.Create(_recordsTotal));
            //create an json-array
            jsa := TJsonArray.Create();
            //add array to object
            while not ds.eof do begin
                //add items to the _first_ elemet of array
                jsoItem := TJsonObject.Create();
                //add object pairs
                jsoItem.AddPair(TJsonPair.Create('DT_RowId',TJsonString.Create(ds.FieldByname('pront').AsString)));
                jsoItem.AddPair(TJsonPair.Create('pront', TJsonString.Create(ds.FieldByname('pront').AsString)));
                jsoItem.AddPair(TJsonPair.Create('nome', TJsonString.Create(ds.FieldByname('nome').AsString)));

                jsoItem.AddPair(TJsonPair.Create('endereco', TJsonString.Create(ds.FieldByname('endereco').AsString)));
                jsoItem.AddPair(TJsonPair.Create('bairro', TJsonString.Create(ds.FieldByname('bairro').AsString)));
                jsoItem.AddPair(TJsonPair.Create('cidade', TJsonString.Create(ds.FieldByname('cidade').AsString)));
                jsoItem.AddPair(TJsonPair.Create('estado', TJsonString.Create(ds.FieldByname('estado').AsString)));
                jsoItem.AddPair(TJsonPair.Create('telefone', TJsonString.Create(ds.FieldByname('telres').AsString)));
                jsoItem.AddPair(TJsonPair.Create('convenio', TJsonString.Create(ds.FieldByname('convenio').AsString)));
                jsoItem.AddPair(TJsonPair.Create('cpf', TJsonString.Create(ds.FieldByname('cpf').AsString)));
                jsoItem.AddPair(TJsonPair.Create('email', TJsonString.Create(ds.FieldByname('email').AsString)));
                //put it into array
                jsa.AddElement(jsoItem);
                ds.Next;
            end;
            jsp := TJSONPair.Create('data', jsa);
            jso.AddPair(jsp);

            result:=jso;
end;

This is the result of the function:

{
    "draw": 3,
    "recordsTotal": 5303,
    "recordsFiltered": 5303,
    "data": [{
        "DT_RowId": "2582",
        "pront": "2582",
        "nome": "XXXXX",
        "endereco": "RUA TEODORO DA SILVA,333/103",
        "bairro": "VILA ISABEL",
        "cidade": "RIO DE JANEIRO",
        "estado": "RJ",
        "telefone": "3683*2690",
        "convenio": "GOLDEN CROSS ( B)",
        "cpf": "",
        "email": ""
    }, {
        "DT_RowId": "2818",
        "pront": "2818",
        "nome": "YYYYY",
        "endereco": "RUA PEREIRA NUNES , 395 AP 308",
        "bairro": "VILA ISABEL",
        "cidade": "RIO DE JANEIRO",
        "estado": "RJ",
        "telefone": "YYYYY",
        "convenio": "UN",
        "cpf": "216820707-00",
        "email": ""
    }, {
        "DT_RowId": "1015",
        "pront": "1015",
        "nome": "YYYYYY",
        "endereco": "rua francisca zieze, 192",
        "bairro": "aboliçao",
        "cidade": "RIO DE JANEIRO",
        "estado": "RJ",
        "telefone": "25945909",
        "convenio": "UN",
        "cpf": "71883592704",
        "email": ""
    }, {
        "DT_RowId": "1701",
        "pront": "1701",
        "nome": "JJJJJJ",
        "endereco": "AV 28 DE SETEMBRO 163 APT 704",
        "bairro": "VILA ISABEL",
        "cidade": "RIO DE JANEIRO",
        "estado": "RJ",
        "telefone": "2253-7625",
        "convenio": "PETROBRAS DISTR\ ( R)",
        "cpf": "",
        "email": ""
    }, {
        "DT_RowId": "1076",
        "pront": "1076",
        "nome": "LLLLLLLL",
        "endereco": "RUA ARISTIDES ,241/304",
        "bairro": "MEIER",
        "cidade": "RIO DE JANEIRO",
        "estado": "RJ",
        "telefone": "2501*6600",
        "convenio": "CORREIOS",
        "cpf": "",
        "email": ""
    }, {
        "DT_RowId": "5959",
        "pront": "5959",
        "nome": "ZULEICA IIIII",
        "endereco": "rua dos araujos 11a, bl 02 ap 301",
        "bairro": "tijuca",
        "cidade": "RIO DE JANEIRO",
        "estado": "RJ",
        "telefone": "2254-5682",
        "convenio": "AMIL",
        "cpf": "53150457734",
        "email": ""
    }, {
        "DT_RowId": "5894",
        "pront": "5894",
        "nome": "ZULEICA AAAAA",
        "endereco": "RUA PROF GABIZO,332/102",
        "bairro": "TIJUCA",
        "cidade": "RIO DE JANEIRO",
        "estado": "RJ",
        "telefone": "2568*9654",
        "convenio": "UNIMED (SCOFANO)",
        "cpf": "54016843715",
        "email": ""
    }, {
        "DT_RowId": "4034",
        "pront": "4034",
        "nome": "ZILENE KAKAKA",
        "endereco": "RUA AFONSO FERREIRA ,162",
        "bairro": "ENGENHO DE DENTRO",
        "cidade": "RIO DE JANEIRO",
        "estado": "RJ",
        "telefone": "2597*2352",
        "convenio": "CORREIOS",
        "cpf": "",
        "email": ""
    }, {
        "DT_RowId": "5126",
        "pront": "5126",
        "nome": "ZILDA MAMAMA",
        "endereco": "AV DOM HELDER CAMARA 1201",
        "bairro": "BENFICA",
        "cidade": "RIO DE JANEIRO",
        "estado": "RJ",
        "telefone": "7646-0691",
        "convenio": "BRADESCO (B)",
        "cpf": "",
        "email": ""
    }, {
        "DT_RowId": "4497",
        "pront": "4497",
        "nome": "ZILDA LALALA",
        "endereco": "RUA SABARRETO , 13 CASA",
        "bairro": "FONSECA - NITEROI",
        "cidade": "RIO DE JANEIRO",
        "estado": "RJ",
        "telefone": "2721-6646",
        "convenio": "UNIMED (SCOFANO)",
        "cpf": "",
        "email": ""
    }]
}

Answer 1

from svn https://svn.code.sf.net/p/alcinoe/code/ (you can find inside the unicode string implementation also but i prefere to gave here the ansiString as reference)

{******************************************************************************************}
// https://developer.mozilla.org/en-US/docs/JavaScript/Guide/Values,_variables,_and_literals
function  ALJavascriptEncode(const Src: AnsiString; const useNumericReference: boolean = True): AnsiString;
var i, l: integer;
    Buf, P: PAnsiChar;
    ch: Integer;
begin
  Result := '';
  L := Length(src);
  if L = 0 then exit;
  if useNumericReference then GetMem(Buf, L * 6) // to be on the *very* safe side
  else GetMem(Buf, L * 2); // to be on the *very* safe side
  try
    P := Buf;
    for i := low(Src) to high(Src) do begin
      ch := Ord(src[i]);
      case ch of
        8: begin // Backspace
             if useNumericReference then begin
               ALStrMove('\u0008', P, 6);
               Inc(P, 6);
             end
             else begin
               ALStrMove('\b', P, 2);
               Inc(P, 2);
             end;
           end;
        9: begin // Tab
             if useNumericReference then begin
               ALStrMove('\u0009', P, 6);
               Inc(P, 6);
             end
             else begin
               ALStrMove('\t', P, 2);
               Inc(P, 2);
             end;
           end;
        10: begin // New line
              if useNumericReference then begin
                ALStrMove('\u000A', P, 6);
                Inc(P, 6);
              end
              else begin
                ALStrMove('\n', P, 2);
                Inc(P, 2);
              end;
            end;
        11: begin // Vertical tab
              if useNumericReference then begin
                ALStrMove('\u000B', P, 6);
                Inc(P, 6);
              end
              else begin
                ALStrMove('\v', P, 2);
                Inc(P, 2);
              end;
            end;
        12: begin // Form feed
              if useNumericReference then begin
                ALStrMove('\u000C', P, 6);
                Inc(P, 6);
              end
              else begin
                ALStrMove('\f', P, 2);
                Inc(P, 2);
              end;
            end;
        13: begin // Carriage return
              if useNumericReference then begin
                ALStrMove('\u000D', P, 6);
                Inc(P, 6);
              end
              else begin
                ALStrMove('\r', P, 2);
                Inc(P, 2);
              end;
            end;
        34: begin // Double quote
              if useNumericReference then begin
                ALStrMove('\u0022', P, 6);
                Inc(P, 6);
              end
              else begin
                ALStrMove('\"', P, 2);
                Inc(P, 2);
              end;
            end;
        38: begin // & ... we need to encode it because in javascript ' or & will be converted to ' and error unterminated string
              ALStrMove('\u0026', P, 6);
              Inc(P, 6);
            end;
        39: begin // Apostrophe or single quote
              if useNumericReference then begin
                ALStrMove('\u0027', P, 6);
                Inc(P, 6);
              end
              else begin
                ALStrMove('\''', P, 2);
                Inc(P, 2);
              end;
            end;
        60: begin // < ... mostly to hide all </script> tag inside javascript.
                  // http://www.wwco.com/~wls/blog/2007/04/25/using-script-in-a-javascript-literal/
              ALStrMove('\u003C', P, 6);
              Inc(P, 6);
            end;
        62: begin // > ... mostly to hide all HTML tag inside javascript.
              ALStrMove('\u003E', P, 6);
              Inc(P, 6);
            end;
        92: begin // Backslash character (\).
              if useNumericReference then begin
                ALStrMove('\u005C', P, 6);
                Inc(P, 6);
              end
              else begin
                ALStrMove('\\', P, 2);
                Inc(P, 2);
              end;
            end;
        else Begin
          P^:= AnsiChar(ch);
          Inc(P);
        end;
      end;
    end;
    SetString(Result, Buf, P - Buf);
  finally
    FreeMem(Buf);
  end;
end;