node 服务器响应 json

var http = require("http");

var server = http.createServer(function (request, response) {
    response.writeHead(200, { "Content-type": "application/json" })

    var json = {
        name: "xiaoming",
        gender: "male",
        age: 20
    }

    response.write(JSON.stringify(json));
    response.end();

});

server.listen(4000, "127.0.0.1");

server.on("error", function (e) {

    if (e.code == "EADDRINUSE") {
        console.log("in error")
        setTimeout(function () {
            server.close();
            server.listen(4000, "127.0.0.1")
        }, 1000);
    }
})

console.log("server has started")