“Uncaught SyntaxError: Unexpected token <” afte

问题:

I am trying to do AJAX using jQuery with an ODATA REST service provided by an SAP backend system.

          $.ajax({
                type: 'GET',
                url: 'http://sapxx.sapms/sap/opu/odata/.../',                   
                async: true,
                dataType: 'jsonp',                  
                username: 'username',
                password: 'password',
                crossDomain: true,                  
                success: function() {
                    alert('Done.');
                },
                error: function() {
                    alert('Error.');
                },
            });

The request returns status 200 and I get a response from the server which is called something like "?callback=jQuery3100687..." and contains xml code. All this is visible in the Chrome debugger. But after the successful HTTP Request I get the aforementioned error

Uncaught SyntaxError: Unexpected token <

I suspect the error is due to the "dataType" parameter which is set to "jsonp" in the request. Is there any way to work around this error? The server can only respond using XML format. The request only works when the dataType is set to "jsonp", I guess because it enables CORS. After sending the request, I get the "Error" alert despite the 200 status.

回答1:

You say you get an xml response from the server. Your ajax request is set up for jsonp, though:

dataType: 'jsonp',

Try this instead:

dataType: 'xml',
success: function(xml) {
    //remainder of the code
}

If you set the dataType to jsonp, jQuery will try to parse the response as JSON. This results in errors, because the response ins't JSON.