Pass Multiple Parameters to jQuery ajax call

Don’t use string concatenation to pass parameters, just use a data hash:

$.ajax({
    type: 'POST',
    url: 'popup.aspx/GetJewellerAssets',
    contentType: 'application/json; charset=utf-8',
    data: { jewellerId: filter, locale: 'en-US' },
    dataType: 'json',
    success: AjaxSucceeded,
    error: AjaxFailed
});

---

UPDATE:

As suggested by @Alex in the comments section, an ASP.NET PageMethod expects parameters to be JSON encoded in the request, so JSON.stringify should be applied on the data hash:

$.ajax({
    type: 'POST',
    url: 'popup.aspx/GetJewellerAssets',
    contentType: 'application/json; charset=utf-8',
    data: JSON.stringify({ jewellerId: filter, locale: 'en-US' }),
    dataType: 'json',
    success: AjaxSucceeded,
    error: AjaxFailed
});