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feature: Implement type guard in the isEnum() function #2300

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feature: Implement type guard in the isEnum() function#2300
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flag: needs discussionIssues which needs discussion before implementation.type: featureIssues related to new features.

Description

@kterui9019
kterui9019
opened on Nov 3, 2023

Description

The isEnum() function does not implement type guard.
This is inconvenient when writing code like the following

const somefunction(value: string): USERTYPE => {
  if (!isEnum(value, USERTYPE)) throw new Error("not match enum");
  return value; // Type 'string' is not assignable to type 'USERTYPE'. ts(2322)
}

Proposed solution

A type guard should be implemented in the isEnum() function.
I am now wrapping the isEnum() function in the type guard function myself.

function validateEnumValue<T>(value: any, enumeration: T): value is T[keyof T] {
  return isEnum(value, enumulation);
}

Activity

  1. kterui9019
    added
    flag: needs discussionIssues which needs discussion before implementation.
    type: featureIssues related to new features.
    on Nov 3, 2023

  2. kterui9019 commented on Nov 3, 2023

    @kterui9019
    kterui9019
    on Nov 3, 2023
    Author

    Specifically, I believe this can be accomplished by modifying the code as follows.

    export function isEnum<T extends Record<string | number, unknown>>(value: unknown, entity: T): value is T[keyof T]  {
  const enumValues = Object.values(entity);
  return enumValues.includes(value);
}

    I can send you a pull request if you like.

  3. braaar commented on Jan 11, 2024

    @braaar
    braaar
    on Jan 11, 2024
    Member

    I'm moving this to the discussion tab, as we are trying to keep the issue count low. Please see this issue for an explanation.

  4. typestack
    locked and limited conversation to collaborators on Jan 11, 2024
  5. braaar
    converted this issue into a discussion #2365 on Jan 11, 2024
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