Bundle size impact for different solutions

The whole article – With or without enums in TypeScript

Comparison

Approach	Enum	Const enum	Const enum + preserveConstEnums	Object + as const	Union type
Numeric values	126	44	112	80	44
Heterogeneous values	124	48	117	83	48
String values	116	49	108	83	49

When you need to keep lookup object (enum, const enum + preserveConstEnums and object + as const), the optimal solution is always an object + as const.

When you don't need a lookup object (const enum and union type), both const enum and union type are optimal.

Way to compare

1. TypeScript Playground to get JS output

2. size-limit to calculate the size of each JS files

Examples

Enums:

1. Numeric enum
2. Heterogeneous enum
3. String enum

Const enums:

1. Numeric const enum
2. Heterogeneous const enum
3. String const enum

Const enums + enabled preserveConstEnums:

1. Numeric const enum
2. Heterogeneous const enum
3. String const enum

Objects + as const:

1. Numeric object + as const
2. Heterogeneous object + as const
3. String object + as const

Union types:

1. Numeric union type
2. Heterogeneous union type
3. String union type