前言

最近在学习node+express时写一个小小的服务时，真的是发现万事开头难，真的是一脸懵逼，好好学吧，里边烫过的坑记录下来，方便自己学习。

先看看报的错

GET /users/api/getVerificationCode?phone=1233 500 161.231 ms - 48
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at ServerResponse.setHeader (_http_outgoing.js:518:11)
    at ServerResponse.header (D:\NodesProject\expressDemo\demoApp\node_modules\express\lib\response.js:767:10)
    at ServerResponse.send (D:\NodesProject\expressDemo\demoApp\node_modules\express\lib\response.js:170:12)
    at done (D:\NodesProject\expressDemo\demoApp\node_modules\express\lib\response.js:1004:10)
    at Object.exports.renderFile (D:\NodesProject\expressDemo\demoApp\node_modules\jade\lib\index.js:374:12)
    at View.exports.__express [as engine] (D:\NodesProject\expressDemo\demoApp\node_modules\jade\lib\index.js:417:11)
    at View.render (D:\NodesProject\expressDemo\demoApp\node_modules\express\lib\view.js:135:8)
    at tryRender (D:\NodesProject\expressDemo\demoApp\node_modules\express\lib\application.js:640:10)
    at Function.render (D:\NodesProject\expressDemo\demoApp\node_modules\express\lib\application.js:592:3)
    at ServerResponse.render (D:\NodesProject\expressDemo\demoApp\node_modules\express\lib\response.js:1008:7)

报错翻译

Cannot set headers after they are sent to the client 发送到客户端后无法设置标头

后来发现是因为每次请求完成后没有释放连接或者return，这样导致多余的响应，所以加一个return,看看我的处理办法

//生成手机登录验证码并返回
router.get('/api/getVerificationCode', (req, res, next) => {
  let params = req.query || req.params;
  let userPhone = params.phone;
  let _res = res;
  if (userPhone == undefined || userPhone == "") {
    let volaid = {
      code: 500,
      msg: "手机号不能为空"
    }
    responseJSON(_res, volaid);
这里如果不加return就会报哪个错，因为会多余的响应
    return false;
  };
  testPhoneNum(_res,userPhone);
  let VerificationCode = Math.random().toFixed(6).slice(-6);
  userCode[userPhone] = VerificationCode;
  let codeData = {
    code: 200,
    msg: VerificationCode
  };
  responseJSON(_res, codeData);
});