jquery – 这个JSON结构何时被转换为所有字符串？

这是我的节点/快递代码：

var express = require('express');

var app = express();
app.enable("jsonp callback");
app.use(express.bodyParser());

// allow cross origin scripting to get data from devices directly
app.all('*',function(req,res,next) {
  res.header('Access-Control-Allow-Origin','*');
  res.header('Access-Control-Allow-Methods','PUT,GET,POST,DELETE,OPTIONS');
  res.header('Access-Control-Allow-Headers','Content-Type');
  next();
});

app.post('/departures',res) {

/* I started using this to convert back to integers - but need to solve the problem
    for (var i in req.body.data) {
      req.body.data[i].siteid = parseInt(req.body.data[i].siteid);
    }
*/
    console.log('saving data '+JSON.stringify(req.body.data));
    positionProvider.save(req.body.data,function(){
      res.json({status:'success'});
    })
});

这是我如何用jquery发帖：

var data = [{"siteid":123}];

    $.ajax({
        type: 'POST',url: serverUrl + '/departures',data: {
            data: data
        },success: function(resp) {
            alert('saved departure data '+JSON.stringify(data))
        },error: function(err) {
            console.log('error posting to server...');
            console.log(err);
        }
    });

jquery端报告它发送{“siteid”：123},但节点端报告它收到{“siteid”：“123”}.

整数被转换成字符串在哪里？