Question

注意：我将我的expressjs代码转换为ES6模块。编译器还没有抱怨，我很惊讶。我想我们可以做到这一点，而不必使用.mjs文件扩展名或将类型模块放入服务器文件夹内的package.json中？

我正在使用

Node 14.4.0
typescript: 3.9.7

无论如何回到我的问题。不确定如何键入expressJS东西，例如，我在这里得到No overload matches this call：

我的意思是，如果说没有这样的回调，为什么人们以这种方式使用代码？我很确定这是app.listen过去检查此类错误的有效代码

服务器 / server.ts

import cluster from 'cluster';

import os from 'os';

import App from './api.js';

const port = process.env.PORT || 3000;

if (cluster.isMaster) {
    for (let i = 0; i < os.cpus().length; i++) {
        cluster.fork();
    }
    console.log('Ready on port %d', port);
} else {
    App.listen(port, (err) => {
        console.log(`express is listening on port ${port}`);
        if (err) {
            console.log('server startup error');
            console.log(err);
        }
    });
}

服务器 / api.ts

import historyApi from 'connect-history-api-fallback';
import compression from 'compression';
import countryTable from './data/countries.json';
import express from 'express';
import companyTable from './data/companies.json';
import _ from 'lodash';

const App = express()
.use(compression())
.on('error', (err: any) => {
    console.log(err);
})
.get('/api/v1/countries', (_req: any, res: any) => {
    res.json(countryTable.map((country: any) => _.pick(country, ['id', 'name', 'images'])));
})
.get('/api/v1/companies', (_req: any, res: any) => {
    res.json(
        companyTable.map((company: any) =>
            _.pick(company, [
                'id',
                'active',
                'images',
                'locations',
            ])
        )
    );
})
.use(historyApi())
.use(express.static('dist'))
.use((_req: any, res: any) => {
    res.header('Access-Control-Allow-Origin', '*');
    res.header('Access-Control-Allow-Credentials', true);
    res.header('Access-Control-Allow-Methods', 'GET,OPTIONS');
    res.header(
        'Access-Control-Allow-Headers',
        'Origin,X-Requested-With,Content-Type,Accept,content-type,application/json'
    );
    res.send('Sorry, Page Not Found');
});

export default App;

服务器 / tsconfig.json

{
    "extends": "../../tsconfig",
    "compilerOptions": {
        "outDir": "../../dist/server",                        /* Redirect output structure to the directory. */
        "rootDir": "."                         /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
    },
    "include": ["./*.ts"],
    "resolveJsonModule": true
}

./ tsconfig.json

{
  "compilerOptions": {
    /* Visit https://aka.ms/tsconfig.json to read more about this file */
    "target": "ES2015",                     /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
    "module": "es2020",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
    "lib": ["es5", "es6", "dom"],                      /* Specify library files to be included in the compilation. */
    "moduleResolution": "node",
    "allowJs": true,                     /* Allow javascript files to be compiled. */
//      "checkJs": true,                     /* Report errors in .js files. */
    "jsx": "react",
    "noImplicitAny": true,
    "sourceMap": false,                   /* Generates corresponding '.map' file. */
    "rootDir": "./",                     /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
    "removeComments": true,              /* Do not emit comments to output. */
    "strict": true,                      /* Enable all strict type-checking options. */
    "noUnusedLocals": true,                /* Report errors on unused locals. */
    "noUnusedParameters": true,            /* Report errors on unused parameters. */
//    "rootDirs": ["."],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
    "typeRoots": [
      "node_modules/@types"
    ],                      /* List of folders to include type definitions from. */
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
    "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
    "resolveJsonModule": true,
    "skipLibCheck": true,                     /* Skip type checking of declaration files. */
    "forceConsistentCasingInFileNames": true
    },
    "include": [
        "src"
    ],
    "exclude": [
        "/node_modules",
        "/src/server",
        "/src/client/js/ink-config.js",
        "**/test",
        "dist"
  ]
}

Answer 1

该错误告诉您listen()回调没有任何参数。正确的代码应为：

App.listen(port, () => {
    console.log(`express is listening on port ${port}`);
});

基本上删除错误参数（err）及其相关的任何内容，因为它不存在。

该错误由on('error')方法捕获。但是您已经定义了它，所以应该可以。

您不能完全打印出“服务器启动错误”，因为on('error')方法捕获了所有错误，而不仅仅是服务器启动。但是您可以捕获并显示特定的错误：

// in api.ts:

.on('error', (err: any) => {
    if (e.code === 'EADDRINUSE') {
        console.log('server startup error: address already in use');
    }
    else {
        console.log(err);
    }
})

这是正确的，并且不是打字稿表达类型中的错误。 Express只调用节点的http.Server.listen()，后者依次调用net.Server.listen()，其回调实际上没有传递错误参数。

有关诸如EADDRINUSE之类的系统错误的列表，请参见：https://nodejs.org/api/errors.html#errors_common_system_errors

有关特定于node.js的错误的列表，请参见：https://nodejs.org/api/errors.html#errors_node_js_error_codes

expressJS的TypeScript错误：此调用没有重载

1 个答案: