Using jsonp for cross-origin access under jquery _ jquery

Cross-origin access of the client can be implemented through the jsonp method. jquery provides cross-origin access methods, and jQuery. ajax () supports cross-origin access through get. Of course, cross-origin processing is required on the server. The Code is as follows:

$. Ajax ({
Async: false,
Url: '', // cross-origin URL
Type: 'get ',
DataType: 'jsonp ',
Jsonp: 'jsoncallback', // default callback
Data: mydata, // request data
Timeout: 5000,
BeforeSend: function () {// jsonp mode this method is not triggered. The reason may be that if dataType is specified as jsonp, it is no longer an ajax event.
},
Success: function (json) {// call back function pre-defined by jquery on the client. After obtaining json data on the Cross-origin server, the callback function is dynamically executed.
If (json. actionErrors. length! = 0 ){
Alert (json. actionErrors );
}

},
Complete: function (XMLHttpRequest, textStatus ){

},
Error: function (xhr ){
// Jsonp mode. This method is not triggered.
// Handle request errors
Alert ("request error (Check related network conditions .)");
}
});

The Code is as follows:

$. GetJSON (url + "? Callback =? ",
Function (json ){

});

This method is an advanced encapsulation of the preceding example $. ajax.

On the server side, obtain the callback parameter (for example, jsonp *****) to obtain
Then return the following code: "jsonp ***** (" + json array to be returned + ")";
Jquery will dynamically load and call this through the callback method: jsonp ***** (json array );
This achieves the purpose of cross-Origin data exchange.

JSONP is a Script Injection action, so it also has certain security risks.

Note: jquey does not support cross-origin post.
Reference: http://www.ibm.com/developerworks/cn/web/wa-aj-jsonp1/