Having object data types with primitive declarations leads to issues

Snippet:

export type TestType =
  | string
  | number
  | { value?: string, label?: string }
  | { num1: number, num2: number }
  | null;

const data: TestType;
data?.value // error;

Error Message:

Property 'value' does not exist on type 'TestType'.
  Property 'value' does not exist on type 'string'

Solution Works in Isolation:

const data: TestType = { num1: 10, num2: 20 };
console.log(data.num1); 

However, the issue arises when this type is used in an array of objects where it can be one of the described types at runtime

Answer №1

To resolve this issue, implement the use of the as keyword:

type ItemType = {
  value: string,
  label: string
};

export type NewType =
  | string
  | number
  | ItemType
  | null;

const newData: NewType;

(newData as ItemType)?.value; // This method is effective

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