CODEWITHSUNDEEP
typescriptecmascript-6resharper
Kirsten
Kirsten

Reputation: 18140

Import with 'require' cannot be used when targeting ECMAScript 6 or higher

In VS2019 16.2.1, I created a new project using the Basic Azure Node.js Express 4 Application with TypeScript Template.

Template choice

I can build and run the application.

However, in app.ts, if I hover over the line

import debug = require('debug');

I see a tooltip

Import with 'require' cannot be used when targeting ECMAScript 6 or higher

Warning message

Here is tsconfig.json

  "compilerOptions": {
    "module": "commonjs",
    "target": "es6",
    "lib": ["es6"],
    "sourceMap": true
  },
  "exclude": [
    "node_modules"
  ]
}

Why do I see this message and what should I do about it?

[Update]

I tried changing the first line to

import debug from 'debug';

then I get build errors

app.ts(1,8): error TS1259: Module '"C:/Users/kirst/source/repos/ExpressApp1/ExpressApp1/node_modules/@types/debug/index"' can only be default-imported using the 'esModuleInterop' flag

[Update] The warning dissappears when I suspend Resharper Ultimate.

If I switch to ES5 and try 

import from 'debug'  ( with or without a semicolon )

I see an error 

can only be default-imported using the 'esModuleInterop' flag

esMOdule Interop flag

If I use

import * as debug from 'debug'

It works

Upvotes: 1

Views: 1794

Answers (2)

MarvinJWendt
MarvinJWendt

Reputation: 2684

Instead of using 

import debug = require('debug');

you should use 

import * as debug from 'debug' // Import everything from that module
// OR
import debug from 'debug' // Import only the class 'debug' from that module

// Depends on the module

This is the new Syntax in ES6

(Read more)

If you want to use the old style of importing modules you can set "target" to "ES5" in your tsconfig.json file.

Upvotes: 2

Alex Wayne
Alex Wayne

Reputation: 187134

Sounds like you want to change those imports to this style:

import debug from 'debug';

Or in tsconfig.json set "target" to "ES5" or "ES3".

Upvotes: 1

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