isEnumValue

Checks whether a value is one of the allowed enum values. This helper works with both numeric and string enums.

It never throws and never mutates input. Use it when you need to confirm that a value belongs to a specific enum before running normalization or validation.

Signature

function isEnumValue<T extends Record<string, unknown>>(
  enumObject: T,
  value: unknown
): value is T[keyof T]

Parameters

Name	Data type	Description
enumObject	Record<string, unknown>	The enum-like object whose values define the allowed set.
value	unknown	The value to check. Must match one of the enum’s values to return true.

Returns

A boolean:

• true: If the value is included in Object.values(enumObject).
• false: Otherwise.

Examples

enum Color {
  Red = "red",
  Blue = "blue",
}

isEnumValue(Color, "red")     // true
isEnumValue(Color, "blue")    // true
isEnumValue(Color, "green")   // false
isEnumValue(Color, 123)       // false

enum Status {
  Active = 1,
  Disabled = 2,
}

isEnumValue(Status, 1)        // true
isEnumValue(Status, 3)        // false

For numeric enums, TypeScript generates reverse mappings, which means enum keys may also be treated as valid values:

enum Status {
  Active = 1,
  Disabled = 2,
}

// ["Active", "Disabled", 1, 2]
Object.values(Status)

isEnumValue(Status, "Active") // true

Notes

• Works with both string and numeric enums.
• Uses Object.values(enumObject).includes(value) internally.
• Use normalizeEnum if you need to convert values into enum values.
• Use validateEnum if you need a Result<T> instead of a boolean.

Next up

isError