Error: Cannot find module 'nexmo' & error TS2307: Cannot find module nexmo

Question

so I'm working with the NestJs Framework and typescript .

I was asked to add two factor authentication (SMS) using the node library of Nexmo . Here is a link from their website: https://dashboard.nexmo.com/getting-started/verify

Everything worked as promised while in development mode.

But when I tried to build for production I got this error:

Error: Cannot find module 'nexmo'

So I started googling about it.

I first read about import vs require .

Almost everything in my NestJs project works with import.

But I remember using require sometimes with no problem. For example when I had to use these two I had no problem:

const axios = require('axios');
const xml2js = require('xml2js');

Then I came across people that were having similar problems and they were able to solve them by modifying a bit their tsconfig.json.

Some added the "moduleResolution": "node" instead of "moduleResolution": "classic" while others changed the "module": "commonjs" to "module": "AMD" , or "module": "ESNext"

I tried all of these with no avail. Sometimes the error was changing from:

Error: Cannot find module 'nexmo' 

to:

error TS2307: Cannot find module nexmo

Then I started reading here to understand more about this matter: https://www.typescriptlang.org/docs/handbook/module-resolution.html

Again I couldn't find my solution.

A friend of mine told me to check something about installing typings but NestJs already uses @types which from what I read is a more updated version of typings.

Other than that I had no luck. All I understand is that the project must be compiled to js from ts and that for some reason NestJs can't find the nexmo in the node_modules folder.

Can you help or direct me to the right way?

Answer 1

Ok - tried a few things from a fresh install, and here is what I got to work:

//tsconfig.json

{
  "compilerOptions": {
    "module": "commonjs",
    "declaration": true,
    "removeComments": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true, <- this seems to be the important one here
    "target": "es2017",
    "sourceMap": true,
    "outDir": "./dist",
    "baseUrl": "./",
    "incremental": true
  }
}

//app.controller.ts

import { Controller, Get } from '@nestjs/common';
import { AppService } from './app.service';
import Nexmo from 'nexmo';

const nexmo = new Nexmo({
  apiKey: '',
  apiSecret: '',
});

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

  @Get()
  getHello(): string {
    console.log(nexmo.verify);
    return this.appService.getHello();
  }
}

I then ran

~/G/A/test-nest> master > nest build
~/G/A/test-nest >master >node ./dist/main
[Nest] 21347   - 08/19/2020, 11:36:27 AM   [NestFactory] Starting Nest application...
[Nest] 21347   - 08/19/2020, 11:36:27 AM   [InstanceLoader] AppModule dependencies initialized +18ms
[Nest] 21347   - 08/19/2020, 11:36:27 AM   [RoutesResolver] AppController {}: +7ms
[Nest] 21347   - 08/19/2020, 11:36:27 AM   [RouterExplorer] Mapped {, GET} route +3ms
[Nest] 21347   - 08/19/2020, 11:36:27 AM   [NestApplication] Nest application successfully started +3ms

Answer 2

Looking at the Nexmo package on Github, I see here that it is exporting a default value from its main module: https://github.com/Nexmo/nexmo-node/blob/master/src/Nexmo.js#L175

This means in your typescript file you should be able to simply say:

import Nexmo from 'nexmo';

Some packages in npm are not commonjs friendly (meaning they are not node.js module friendly) and in that case you would need to import that in typescript using this syntax:

import Nexmo = require('nexmo');

Give that first one a shot though and see if it works for you.