Javascript: Replace backslashes with double backslashes

Question

I'm currently having the problem mentioned in the title and I'm somehow not finding a way to properly replace backsashes with double backslashes, so that I can properly give the string to a webservice as parameters. Let me show you what I tried. Some of these do actually work for some other people, but not for me... I'm currently testing this with FF18.0.1

WSParameters.replace(/\\/g, "\\\\\\\\");
WSParameters.replace("\\", "\\\\\\\\");
WSParameters.replace(/\\/g, "\\\\");
WSParameters.replace(/\\/g, "\\");
WSParameters.replace(/\\/g, "\");
WSParameters.replace("\\", "\\\\");

Thanks a lot in advance

EDIT: I should mention that it's somehow parsed into JSON and with firebug I see the backslash in the source string, but not in the JSON view. Maybe there is another way? But somehow it's already failing at the replacement of the backslashes.

EDIT2:

if (noAction == false) {
    $.ajax({
        type: "POST",
        url: "WebService.asmx/" + webMethod,
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        async: pAsync,
        data: WSParameters,
        success: function callFunction(result) { processPOSTResults(result, pType, pNot);},
        error: function (xhr, ajaxOptions, thrownError) {
            alert('Error while communicating with WebAdmin web service. - ' + xhr.status + " " + thrownError);
        }
    });
}

Answer 1

WSParameters.replace(/\\/g, "\\\\"); should do it, and in FF18 as well. Notice that if you use JSON.stringify, this is done automatically. Also watch out that many console outputs (Firebug etc) do surround string contents with quotes, but do not escape them.