/*rowVersion from server*/
var rowVersion = [0, 0, 0, 0, 0, 0, 7, 209];
var json = '';

/*rowVersion hepler*/
$.timeStampToBase64String = function(data) {
    var str = String.fromCharCode.apply(null, data);
    return btoa(str);
};

/*this json post would work just fine, at server rowVersion is as..*/
var modifiedPostObj = {
    RowVersion: $.timeStampToBase64String(rowVersion)
};
json = JSON.stringify(modifiedPostObj);
alert(json);