I'm trying to make a simple API using typescript and NodeJS but when I run my code I get this error
"This module is declared with using 'export =', and can only be used with a default import when using the 'esModuleInterop' flag."
This is my code: package.json
{
"name": "API-Proyecto",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"keywords": [],
"author": "",
"license": "ISC",
"dependencies": {
"cors": "^2.8.5",
"express": "^4.17.1",
"jsonwebtoken": "^8.5.1"
},
"devDependencies": {
"@types/cors": "^2.8.6",
"@types/express": "^4.17.6",
"nodemon": "^2.0.4"
}
}
Index.ts
import express from 'express';
import { Request, Response } from 'express';
import cors from 'cors';
const app = express();
app.use(express.urlencoded({extended: true}));
app.use(express.json);
app.use(cors({origin: true, credentials: true}));
app.get('/api/auth/testing', (req: Request, res: Response) =>{
res.status(200).json({
ok : true,
msg : 'hi from my method'
});
});
app.listen(3000, () => {console.log('Server running on 3000' )});
tsconfig.json
{
"compilerOptions": {
"target": "es6", /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
"module": "commonjs", /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
"outDir": "./dist", /* Redirect output structure to the directory. */
"esModuleInterop": true, /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
}
}
FWIW, I found that switching from
import * as blah from 'blah-lib';
To
const blah = require('blah-lib');
Fixed the issue at compile time.
I solved the problem by compiling the whole file instead of compiling individual files.
Just run the following command to compile the whole file in a go
npx tsc
This should solve your problem
Use:
import * as express from 'express';
Don't forget to set "moduleResolution": "node" in the tsconfig.json if you are using node.
My problem was that I tried to run tsc as tsc -w index.ts.
However, as said here https://stackoverflow.com/a/33244030/5711655 if you run tsc with a specified input file, it won't use the tsconfig.json in your project directory! So in my case I had to use tsc -w.
I was wondering a lot but a friend helped me:
Package.json
{
"name": "api-proyecto",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
**"build-dev": "tsc -w"**
},
"author": "",
"license": "ISC",
"devDependencies": {
"@types/cors": "^2.8.6",
"@types/express": "^4.17.6"
},
"dependencies": {
"cors": "^2.8.5",
"express": "^4.17.1"
}
}
To run your script you need to type the following line
npm i run build-dev (because it's the name of our command)
Finally in another powershell launch node normally. For Example:
node .\dist\index.js
Your code is perfectly fine.
When you make changes to tsconfig, sometimes you need to restart your IDE or Code Editor 🌹