Typescript error: Cannot assign type 'undefined' to type 'string | number | symbol'

I need help figuring out how to address a TypeScript error in my code. Here's the scenario:

export type status = 'success' | 'error' | undefined;

There is an object that maps to different icons based on the status.

const iconsMap: Record<status, React.ReactSVGElement> = {
  error: ErrorIcon,
  success: SuccessIcon,
};

The issue arises because there is no key for undefined in the iconsMap, leading to a TypeScript error message:

Type 'string | undefined' does not satisfy the constraint 'string | number | symbol'. Type 'undefined' is not assignable to type 'string | number | symbol'.

Can anyone provide guidance on how to resolve this error?

typescriptcasting

Answer №1

To avoid including `undefined` in the iconsMap, you can utilize the `NonNullable` utility type as outlined in the TypeScript documentation:

const iconsMap: Record<NonNullable<status>, React.ReactSVGElement> = {
  error: ErrorIcon,
  success: SuccessIcon,
};

It's important to note that the error is not due to a missing key for `undefined`, but rather because the generic type constraint of `Record` only allows for types `string`, `number`, or `symbol`.

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