express-error.js

var express = require('express')
require('express-async-errors')
var app = express()
var pE = require("./promisifyError")

var rt = express.Router();

app.get('/', async function (req, res, next) {
    await pE();
})

app.use("/api", rt)

// 沒有 require('express-async-errors') 就要自己包 try catch
// app.get('/', async function (req, res, next) {
//     try{
//         await pE();
//     }catch(error){
//         next(error)
//     }
// })

app.use((req, res, next) => {
    console.log("will I be called?", "no")
})

app.use((err, req, res, next) => {
    console.log("will I be called?", "yes")
    next(err)
})

// Error Handling 必須宣告於最後面
// 且必須是 (err, req, res, next) => {} 四個參數
// 這也是 Express 蠻奇怪的地方
app.use((err, req, res, next) => {
    console.log("error", err);
    res.send(500, "ServerError")
})

app.listen(3001)