CORS (Cross Origin Resource Sharing) issues are caused when the origin does not match the destination address / host name and the server has not specified that this behavior is allowed. The simple solution to this is to make the server (this case a asmx service) return the header that allows your origin. If you have a domain you are running this from you can specify this domain, otherwise you need only specify the * wildcard to allow all origins.
I haven't written asmx before however i think a solution could look like :
Response.AddHeader("Access-Control-Allow-Origin","*")
Hope this helps