打字稿的NodeJS類型錯誤：無法讀取的不確定

Question

我是新來的TS財產「地址」，所以我不知道爲什麼它隨地吐痰的錯誤

VanillaJS版本的作品就好了。 轉移到TypeScript。 錯誤在我的index.ts中。使用tsc命令編譯TS代碼的 仍然相同。 如果我在構造函數（）中使用console.log（this.server），通常會輸出對象 ，但是當我在theListening（）上使用console.log（this.server）時，它說未定義它的奇怪。

app.ts文件

import * as express from 'express' 
import * as http from 'http' 
import * as bodyParser from 'body-parser' 
import * as cookieParser from 'cookie-parser' 
import * as path from 'path' 
import indexRoutes from './routes/index' 
import userRoutes from './routes/users' 

class App { 

    public express 

    constructor() { 
    this.express = express() 
    this.middleware() 
    this.mountRoutes() 
    this.errorHandler() 
    } 

    private middleware(): void { 
    this.express.use(bodyParser.json()) 
    this.express.use(bodyParser.urlencoded({ extended: false })) 

    this.express.use(cookieParser()) 
    this.express.use(express.static(path.join(__dirname, 'public'))) 
    } 

    private mountRoutes(): void { 
    this.express.use('/', indexRoutes) 
    this.express.use('/users', userRoutes) 
    } 

    private errorHandler(): void { 
    this.express.use((req, res, next) => { 
     let err:any = new Error('Not Found') // I don't know why the err var needs the :any type to work with err.status below it. Without the :any type err.status is spitting errors hahaha 
     err.status = 404 
     next(err) 
    }); 

    this.express.use((err, req, res, next) => { 
     res.locals.message = err.message 
     res.locals.error = req.app.get('env') === 'development' ? err : {} 

     res.status(err.status || 500) 
     res.json({ 
     message: 'Error' 
     }) 
    }) 
    } 
} 

export default new App().express 

index.ts文件

import app from './app' 
import * as debug from 'debug' 
import * as http from 'http' 

class Server { 

public server 

public port 

public debug 

constructor() { 
    this.debug = debug('myexpress:server') 
    this.port = this.normalizePort(process.env.PORT || '3000') 
    app.set('port', this.port) 
    this.server = http.createServer(app) 
    this.server.listen(this.port) 
    this.server.on('error', this.onError) 
    this.server.on('listening', this.onListening) 
} 

private normalizePort(val): any { 
    let port = parseInt(val, 10) 

    if (isNaN(port)) { 
    return val 
    } 

    if (port >= 0) { 
    return port 
    } 

    return false 
} 

private onError(error): void { 
    if (error.syscall !== 'listen') { 
    throw error 
    } 

    let bind = typeof this.port === 'string' ? 'Pipe ' + this.port : 'Port' + 
    this.port 

    switch (error.code) { 
    case 'EACCES': 
     console.error(bind + ' requires elevated privileges') 
     process.exit(1) 
     break 

    case 'EADDRINUSE': 
     console.error(bind + ' is already in use') 
     process.exit(1) 
     break 

    default: 
     throw error 
    } 
} 

public onListening(): void { 
    let addr = this.server.address() << THIS RIGHT HERE 

    let bind = typeof addr === 'string' ? 'pipe ' + addr : 'port ' + 
    addr.port 

    debug('Listening on ' + bind) 
    } 
} 

new Server() 

Answer 1

首先，使用。對時（監聽器）的方法結合到權利範圍。

this.server.on('listening', this.onListening.bind(this)) 

或

this.server.on('listening', (e) => this.onListening(e))