Unable to write ES6 syntax in Node Typescript app

Question

I am getting an exception while importing module

Here is code

import * as express from 'express';

export class Server {

    app: express.Application
    constructor() {
        const port = 3000 || process.env.PORT
        this.app = express()
        this.app.listen(port, () => {
            console.log(`Listening on Port: ${port}`)
        })
    }
}

export default new Server()

Note: I am creating API with Angular 7, both client & server apps have common node_modules and other configuration files like package.json and angular.json

The same code, I am running with Angular 6 is working fine. Is there any configuration issue?

Update 1:

Old Angular 6 project, I created with Node v8.9.3 and new Angular 7 project with Node v10.14.2 and facing issue that server code is running with old project but giving stated error with new project.

Update 2:

When I changed it to

var express = require("express");

const app = express()
const port = 3001 || process.env.PORT
app.listen(port, () => {
    console.log(`Listening on Port: ${port}`)
})

module.exports = app;

It worked fine... but I need to use ES6 syntax

Answer 1

I think i figured it out:

Node does not allow ECMAScriptModules yet (experimental)

So instead of this:

import * as express from "express";

you should use this:

var express = require("express");

But you can use the flag --experimental-modules to make it compile (its not stable yet).

See this Question

Answer 2

It could be problem in tsconfig.json. Check compilerOptions.module. Example:

   {
  "compileOnSave": false,
  "compilerOptions": {
    "baseUrl": "./",
    "outDir": "./dist/out-tsc",
    "sourceMap": true,
    "declaration": false,
    "module": "commonjs",
    "moduleResolution": "node",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "importHelpers": true,
    "target": "es5",
    "typeRoots": [
      "node_modules/@types"
    ],
    "lib": [
      "es2018",
      "dom"
    ]
  }
}