Convert an Enum to a String or a Number in TypeScript

# Convert an Enum to a String or a Number in TypeScript

To convert a numeric enum to a string, use bracket notation to access a specific value on the enum to get its name, e.g. NumericEnum[NumericEnum.Yes].

Similarly, you can convert a string enum to a string by using dot notation to access a specific property.

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// ✅ NUMERIC Enums
enum NumericEnum {
  Yes,
  No,
  Maybe,
}

// 👇️ to string
const str = NumericEnum[NumericEnum.Yes];
console.log(str); // 👉️ "Yes"

// 👇️ to number
const num = NumericEnum.Yes;
console.log(num); // 👉️ 0

If you have a String Enum, use the following code sample instead.

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// ✅ STRING Enums
enum StringEnum {
  Yes = 'Y',
  No = 'N',
  Maybe = 'M',
}

// 👇️ to string
const str = StringEnum.Yes;
console.log(str); // 👉️ "Y"

The first enum in the example is a numeric enum, where the Yes property points to a value of 0, No points to a value of 1 and Maybe to a value of 2.

# Converting a Numeric enum to a string

With numeric enums, we can use a reverse mapping to access the name of a specific value.

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enum NumericEnum {
  Yes,
  No,
  Maybe,
}

// 👇️ Both lines do the same
console.log(NumericEnum[0]); // 👉️ "Yes"
console.log(NumericEnum[NumericEnum.Yes]); // 👉️ "Yes"

Passing a specific value of the enum between the brackets enables us to convert it to a string by getting the corresponding name.

I've also written an article on how to convert a string to an enum in TS.

# Converting a Numeric enum to a number

If you need to convert a numeric enum to a number, access a specific property using dot notation.

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// ✅ NUMERIC Enums
enum NumericEnum {
  Yes,
  No,
  Maybe,
}

// 👇️ to number
const num = NumericEnum.Yes;
console.log(num); // 👉️ 0
console.log(typeof num); // 👉️ "number"

# Converting a string enum to a string

Similarly, you can convert a string enum to a string by accessing one of the names in the enum using dot notation.

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// ✅ STRING Enums
enum StringEnum {
  Yes = 'Y',
  No = 'N',
  Maybe = 'M',
}

// 👇️ to string
const str = StringEnum.Yes;
console.log(str); // 👉️ "Y"

Note that reverse mappings don't work for string enums. String enum members do not get a reverse mapping generated at all.

Enums are real objects in TypeScript, so you can use the Object.keys() and Object.values() methods to get an array of the enum's names or values.

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// ✅ STRING Enums
enum StringEnum {
  Yes = 'Y',
  No = 'N',
  Maybe = 'M',
}

const names = Object.keys(StringEnum);
console.log(names); // 👉️ ['Yes', 'No', 'Maybe']

const values = Object.values(StringEnum);
console.log(values); // 👉️ ['Y', 'N', 'M']

This works similarly with numeric enums.

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// ✅ NUMERIC Enums
enum NumericEnum {
  Yes,
  No,
  Maybe,
}

const names = Object.keys(NumericEnum).filter((v) => isNaN(Number(v)));
console.log(names); // 👉️ ['Yes', 'No', 'Maybe']

const values = Object.values(NumericEnum).filter((v) => !isNaN(Number(v)));
console.log(values); // 👉️ [0, 1, 2]

However, the Object.keys() method returns an array containing the enum's names and values, so you have to use the filter method to filter out the unnecessary values.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• Convert an Enum to a Union Type in TypeScript
• Use an Enum as Restricted Key or Value type in TypeScript
• How to compare Enums in Typescript
• How to convert a String to Enum in TypeScript
• How to Omit values from an Enum in TypeScript
• How to use a Switch statement with Enums in TypeScript