Ban enums, and replace them with alternatives

.eslintrc.js

@@ -7,6 +7,16 @@ module.exports = {
     {
       files: ['*.ts'],
       extends: ['@metamask/eslint-config-typescript'],
+      rules: {
+        'no-restricted-syntax': [
+          'error',
+          {
+            selector: 'TSEnumDeclaration',
+            message:
+              "Don't use enums. There are a number of reasons why they are problematic, but the most important is that TypeScript treats them nominally, not structurally, and this can cause unexpected breaking changes. Instead, use an object + type, an array + type, or just a type. Learn more here: https://github.com/MetaMask/eslint-config/issues/417",
+          },
+        ],
+      },
     },
 
     {

CHANGELOG.md

@@ -7,6 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- **BREAKING:** Change `KnownCaipNamespace`, `JsonSize`, and `Duration` from enums to object literals + object types
+  - If you are accessing a member of these enums at runtime (e.g. `KnownCaipNamespace.Eip155`), you should not have to change anything, nor should you have any breaking changes.
+  - If you are using the whole enum type within another type or within a function or method signature (e.g. `function resolveRpcMethod(namespace: KnownCaipNamespace) { ... }`), these changes will be breaking for you. Consumers of your library will need to switch to `@metamask/utils` 12.0.0.
+  - Accessing a member of the enum type at compile time as though it were an object (e.g. `function resolveRpcMethod(namespace: KnownCaipNamespace.Eip155) { ... }`) is no longer supported. Use a literal (e.g. `'Eip155'`) instead.
+
 ## [11.11.0]
 
 ### Added

src/caip-types.ts

@@ -131,19 +131,22 @@ export const CaipAssetTypeOrIdStruct = definePattern<
 export type CaipAssetTypeOrId = Infer<typeof CaipAssetTypeOrIdStruct>;
 
 /** Known CAIP namespaces. */
-export enum KnownCaipNamespace {
+export const KnownCaipNamespace = {
   /** BIP-122 (Bitcoin) compatible chains. */
-  Bip122 = 'bip122',
+  Bip122: 'bip122',
   /** Solana compatible chains */
-  Solana = 'solana',
+  Solana: 'solana',
   /** Stellar compatible chains */
-  Stellar = 'stellar',
+  Stellar: 'stellar',
   /** Tron compatible chains */
-  Tron = 'tron',
+  Tron: 'tron',
   /** EIP-155 compatible chains. */
-  Eip155 = 'eip155',
-  Wallet = 'wallet',
-}
+  Eip155: 'eip155',
+  Wallet: 'wallet',
+} as const;
+
+export type KnownCaipNamespace =
+  (typeof KnownCaipNamespace)[keyof typeof KnownCaipNamespace];
 
 /**
  * A CAIP-2 chain ID that is guaranteed to have a known CAIP namespace

src/misc.test-d.ts

@@ -124,13 +124,13 @@ if (hasProperty(hasPropertyTypeExample, 'a')) {
 // getKnownPropertyNames
 //=============================================================================
 
-enum GetKnownPropertyNamesEnumExample {
-  Foo = 'bar',
-  Baz = 'qux',
-}
+const GetKnownPropertyNamesExample = {
+  Foo: 'bar',
+  Baz: 'qux',
+} as const;
 
 expectType<('Foo' | 'Baz')[]>(
-  getKnownPropertyNames(GetKnownPropertyNamesEnumExample),
+  getKnownPropertyNames(GetKnownPropertyNamesExample),
 );
 
 //=============================================================================

src/misc.ts

@@ -130,17 +130,18 @@ export type PlainObject = Record<number | string | symbol, unknown>;
 /**
  * Predefined sizes (in Bytes) of specific parts of JSON structure.
  */
-export enum JsonSize {
-  Null = 4,
-  Comma = 1,
-  Wrapper = 1,
-  True = 4,
-  False = 5,
-  Quote = 1,
-  Colon = 1,
-  // eslint-disable-next-line @typescript-eslint/no-shadow
-  Date = 24,
-}
+export const JsonSize = {
+  Null: 4,
+  Comma: 1,
+  Wrapper: 1,
+  True: 4,
+  False: 5,
+  Quote: 1,
+  Colon: 1,
+  Date: 24,
+} as const;
+
+export type JsonSize = (typeof JsonSize)[keyof typeof JsonSize];
 
 /**
  * Regular expression with pattern matching for (special) escaped characters.

src/time.test.ts

@@ -30,9 +30,7 @@ describe('time utilities', () => {
 
       Object.values(Duration).forEach((duration) => {
         const count = getRandomCount();
-        expect(inMilliseconds(count, duration as Duration)).toBe(
-          count * (duration as Duration),
-        );
+        expect(inMilliseconds(count, duration)).toBe(count * duration);
       });
     });
   });

src/time.ts

@@ -1,42 +1,44 @@
 /**
  * Common duration constants, in milliseconds.
  */
-export enum Duration {
+export const Duration = {
   /**
    * A millisecond.
    */
-  Millisecond = 1,
+  Millisecond: 1,
 
   /**
    * A second, in milliseconds.
    */
-  Second = 1000, // Millisecond * 1000
+  Second: 1000, // Millisecond * 1000
 
   /**
    * A minute, in milliseconds.
    */
-  Minute = 60_000, // Second * 60
+  Minute: 60_000, // Second * 60
 
   /**
    * An hour, in milliseconds.
    */
-  Hour = 3_600_000, // Minute * 60
+  Hour: 3_600_000, // Minute * 60
 
   /**
    * A day, in milliseconds.
    */
-  Day = 86_400_000, // Hour * 24
+  Day: 86_400_000, // Hour * 24
 
   /**
    * A week, in milliseconds.
    */
-  Week = 604_800_000, // Day * 7
+  Week: 604_800_000, // Day * 7
 
   /**
    * A year, in milliseconds.
    */
-  Year = 31_536_000_000, // Day * 365
-}
+  Year: 31_536_000_000, // Day * 365
+} as const;
+
+export type Duration = (typeof Duration)[keyof typeof Duration];
 
 const isNonNegativeInteger = (number: number) =>
   Number.isInteger(number) && number >= 0;