TypeScript import without 'esModuleInterop'

[Baterka]

When importing into TypeScript file with @types/ms installed I am getting:

TS2497: This module can only be referenced with ECMAScript imports/exports by turning on the 'esModuleInterop' flag and referencing its default export.

Sure, I can turn esModuleInterop, but no other module I used had this issue.

Fix can be maybe to update code?

[stefanpl]

@Baterka you can import (without the esModuleInterop flag) by using this syntax:

import ms = require('ms');

[itsMapleLeaf]

The import x = require('x') syntax is discouraged in use for modern code bases, since it's non-standard. Turning on esModuleInterop is the real fix here.

The module is written in CJS, so if you're using ES modules, interop is needed to import it, as a default.

[stefanpl]

@kingdaro thanks for your comment! I had not been aware that the import x = require syntax is non-standard, I'll try to avoid it in the future. Problem is, last time I tried esModuleInterop, it was not working very smoothly. Guess I'll have to do some digging there as well.

Is migrating the ms package to the ES module format an option? I guess that would be the gist of this ticket, wouldn't it?

[Baterka]

Why closed?

[vtrphan]

i'm having problem too. why closed?

[JeromeDeLeon]

Same here, I inserted the allowSyntheticDefaultImports and esModuleInterop but still doing import ms from 'ms' still gives me undefined when accessing it. I scaffolded the project based on the NestJS setup.

{
  "compilerOptions": {
    "module": "commonjs",
    "declaration": true,
    "removeComments": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
    "target": "es2017",
    "sourceMap": true,
    "outDir": "./dist",
    "baseUrl": "./",
    "incremental": true
  }
}
`

[homj]

same for me!
I think this issue should be reopened

[guiseek]

https://www.npmjs.com/package/@types/ms

is this library already typescript in your source? why are you still maintaining the @types/ms project? there should be a notice there stating that it's no longer needed, no?

[guiseek]

the solution might be to install the canary version, like this:
npm i ms@3.0.0-canary.1

and import as follows:
import ms, { StringValue } from 'ms'

are now using string types, the code would look like this:

export class DateInterval {
   public readonly ms: number;

   constructor(interval: StringValue) {
     this.ms = ms(interval);
   }
}