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")