比如你有一個按鈕，然后點擊的時候進行跨域請求：

$('#jsonp_link').click(function(e){
     e.preventDefault();
     $.ajax({
         dataType: 'jsonp',
         data: {"name": "Jack"},
         jsonp: 'callback',
         jsonpCallback: 'myCallback',
         url: 'http://localhost:8888/endpoint',
         success: function(data){
              console.log("Cross-domain succeeds);
         },
         error: function(error){
               alert(error);
          }
       });
  });

function myCallback(data){
    console.log("Cross-domain succeeds: "
      + data.name + " is "+ data.age + " and lives in " + data.place);
}

然后在后端，創(chuàng)建一個API

// Server API
 app.get('/endpoint', function(req,res,next){
      var obj = {};
      obj.age = '27';
      obj.place = 'Beijing';
      obj.name = req.query.name;
      res.header('Content-type','application/json');
      res.header('Charset','utf8');
      res.jsonp(obj);
});

最后就會打印出來：
"Cross-domain succeeds: Jack is 27 and lives in Beijing."