Is it possible to choose the inverse of a user-defined type in Angular?

Is it possible to retrieve the opposite of a specified custom type within a variable using Typescript?

For example, if I define a type like this: type Result = 'table' | 'grid'; Then any variable with the type Result can only be assigned either 'table' or 'grid'.

Is there a way to access the opposite value of 'table', such as 'grid'? Similar to how negation is used with booleans, for instance:

let a = false;
// a is false
a = !a;
// a is true

I'm not looking for the exact same syntax, but rather a similar concept of retrieving the opposite of a specific custom type?

angulartypescripttypes

Answer №1

To define the type explicitly, you can do the following:

type Outcome = 'box' | 'circle';
let box: Outcome = 'box';

let alternative: Exclude<Outcome, typeof box> = 'circle';

In this scenario, alternative will always be of type circle, preventing any other assignment.

Remember, types are static and not accessible during runtime when assigning variables.

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