Is it not possible to stringify an Error using JSON.stringify? The problem is that I end up with an empty object.

 https://stackoverflow.com/questions/18391212/is-it-not-possible-to-stringify-an-error-using-json-stringify

// String-keyed array elements are not enumerable and make no sense in JSON
let a = ['foo', 'bar'];
a['baz'] = 'quux';      // a: [ 0: 'foo', 1: 'bar', baz: 'quux' ]
JSON.stringify(a);
// '["foo","bar"]'

Error object doesn't have its enumerable properties, that's why it prints an empty object

express res 參數說明

https://expressjs.com/zh-tw/api.html#res

res.render的說明

https://codertw.com/%E5%89%8D%E7%AB%AF%E9%96%8B%E7%99%BC/200136/

// ssr error handle基礎框架

export default { // ... hooks: { render: { errorMiddleware(app) { app.use((error, _req, _res, next) => { if (error) { console.log("Logged in errorMiddleware", error); } next(error); }); }, }, }, 

};

// 實際應用

hooks: {

    render: {

      errorMiddleware(app) {

        app.use((error, req, res, next) => {

          // handle ssr error to browser

          if (error) {

            res.writeHead(200, {

              'Content-Length': Buffer.byteLength(JSON.stringify(error, Object.getOwnPropertyNames(error))),  

              'Content-Type': 'text/plain'

            });

              

            res.end(JSON.stringify(error, Object.getOwnPropertyNames(error)));   // Error object doesn't have its enumerable properties, that's why we use replacer. or it'll print an empty object

          } else {

            next(error);

          }

          // setTimeout ok了，timeout就是沒有錯誤而超過時間才會出現，所以直接告訴timeout就可以~~

          res.setTimeout(1000, function(){

            // console.log('Request has timed out.');

            res.writeHead(307, {

              Location: '/timeout'

            });

            res.end();

          });

         

        })

      },

    },

  },