TS1371

error TS1371: This import is never used as a value and must use ‘import type’ because ‘importsNotUsedAsValues’ is set to ‘error’.

Broken Code ❌

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export class MyPerson {
  constructor(public name: string, public age: number) {
  }
}

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import {MyPerson} from './MyPerson';

export function printAge(person: MyPerson) {
  console.log(person.age);
}

Fixed Code ✔️

Solution 1:

When “importsNotUsedAsValues” is set to “error” in your “tsconfig.json”, then you have to use the “import type” syntax when you just want to refer to a type instead of using it as a value:

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import type {MyPerson} from './MyPerson';

export function printAge(person: MyPerson) {
  console.log(person.age);
}

Solution 2:

Use the class also as a value and not just a type:

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import {MyPerson} from './MyPerson';

export function printAge(person: MyPerson) {
  console.log(person.age);
}

const benny = new MyPerson('Benny', 35);
printAge(benny);

Solution 3:

You can also set “importsNotUsedAsValues” to “preserve” which is not recommended.