执行自己的JSONP函数

Question

I am using JSONP , and my url(action) is returning me function called processTemplates. Is there any way I can execute my own function instead of processTemplates.

Something Like _processJSONCallBack

    function _processOverideCallBack(actionName) {
         $.ajax({
                type: 'GET',
                url: actionName,
                async: false,
                contentType: "application/javascript",
                jsonpCallback: '_processJSONCallBack',
                dataType: "jsonp",
                error: function(jqXHR, exception) {
                if (jqXHR.status === 0) {
                    alert('Not connect.\n Verify Network.');
                } else if (jqXHR.status == 404) {
                    alert('Requested page not found. [404]');
                } else if (jqXHR.status == 500) {
                    alert('Internal Server Error [500].');
                } else if (exception === 'parsererror') {
                   alert('Requested JSON parse failed.');
                } else if (exception === 'timeout') {
                    alert('Time out error.');
                } else if (exception === 'abort') {
                    alert('Ajax request aborted.');
                } else {
                    alert('Uncaught Error.\n' + jqXHR.responseText);
                }
            }
        });
};

But when I am trying to do its throwing an exception "Requested JSON parse failed."

Please help me on this.

Answer 1

From the jQuery docs :

Cross-domain requests and dataType: "jsonp" requests do not support synchronous operation

You are probably getting an error because you have async: false .

Answer 2

You can get called with the data from a JSONP Ajax call in a much simpler fashion than you're trying to do because jQuery will do all the work for you of creating a callback function. You can just do this by using a success handler:

function _processOverideCallBack(actionName) {
     $.ajax({
            type: 'GET',
            url: actionName,
            dataType: "jsonp",
            success: function(data) {
                // data will be your already parsed JSONP data here
            },
            error: function(jqXHR, exception) {
                    if (jqXHR.status === 0) {
                    alert('Not connect.\n Verify Network.');
                } else if (jqXHR.status == 404) {
                    alert('Requested page not found. [404]');
                } else if (jqXHR.status == 500) {
                    alert('Internal Server Error [500].');
                } else if (exception === 'parsererror') {
                   alert('Requested JSON parse failed.');
                } else if (exception === 'timeout') {
                    alert('Time out error.');
                } else if (exception === 'abort') {
                    alert('Ajax request aborted.');
                } else {
                    alert('Uncaught Error.\n' + jqXHR.responseText);
                }
            }
    });
};

Also, you cannot use async: false with JSONP. That is not supported due to how JSONP requests work. All JSONP requests must be async.

In addition, please remember that JSONP is a different type of request than a normal Ajax request and your server MUST support the JSONP type request. You can't make a JSONP request of a normal Ajax URL. The server must produce a JSONP formatted response.

Answer 3

jsonpCallback is the parameter name of the callback function when the request is built. Typically a JSONP request looks like this:

http://example.com/endpoint ? callback =yourfunction&foo=bar

Based on your code, jQuery is probably generating something like this:

http://example.com/endpoint ? _processJSONCallBack =yourfunction&foo=bar

Whatever API you're using doesn't know the name of your callback function because it isn't being set in the right parameter. Check the documentation to see what the callback parameter name should be. jQuery defaults to 'callback' if jsonpCallback isn't specified.