feat: add optional configuration parameter to generate native Typescript enums

docs/src/pages/reference/configuration/output.md

@@ -1279,3 +1279,25 @@ module.exports = {
   },
 };
 ```
+
+#### useNativeEnums
+
+Type: `Boolean`
+
+Valid values: true or false. Defaults to false.
+
+Use this property to generate native Typescript `enum` instead of `type` and `const` combo.
+
+Example:
+
+```js
+module.exports = {
+  petstore: {
+    output: {
+      override: {
+        useNativeEnums: true,
+      },
+    },
+  },
+};
+```

packages/core/src/generators/schema-definition.ts

@@ -59,6 +59,7 @@ export const generateSchemasDefinition = (
             resolvedValue.value,
             schemaName,
             resolvedValue.originalSchema?.['x-enumNames'],
+            context.override.useNativeEnums,
           );
         } else if (schemaName === resolvedValue.value && resolvedValue.isRef) {
           // Don't add type if schema has same name and the referred schema will be an interface

packages/core/src/getters/enum.ts

@@ -1,7 +1,23 @@
 import { keyword } from 'esutils';
 import { isNumeric, sanitize } from '../utils';
 
-export const getEnum = (value: string, enumName: string, names?: string[]) => {
+export const getEnum = (
+  value: string,
+  enumName: string,
+  names?: string[],
+  useNativeEnums?: boolean,
+) => {
+  const enumValue = useNativeEnums
+    ? getNativeEnum(value, enumName, names)
+    : getTypeConstEnum(value, enumName, names);
+  return enumValue;
+};
+
+const getTypeConstEnum = (
+  value: string,
+  enumName: string,
+  names?: string[],
+) => {
   let enumValue = `export type ${enumName} = typeof ${enumName}[keyof typeof ${enumName}]`;
 
   if (value.endsWith(' | null')) {
@@ -59,6 +75,49 @@ export const getEnumImplementation = (value: string, names?: string[]) => {
   }, '');
 };
 
+const getNativeEnum = (value: string, enumName: string, names?: string[]) => {
+  const enumItems = getNativeEnumItems(value, names);
+  const enumValue = `export enum ${enumName} {\n${enumItems}\n}`;
+
+  return enumValue;
+};
+
+const getNativeEnumItems = (value: string, names?: string[]) => {
+  if (value === '') return '';
+
+  return [...new Set(value.split(' | '))].reduce((acc, val, index) => {
+    const name = names?.[index];
+    if (name) {
+      return (
+        acc +
+        `  ${keyword.isIdentifierNameES5(name) ? name : `'${name}'`}: ${val},\n`
+      );
+    }
+
+    let key = val.startsWith("'") ? val.slice(1, -1) : val;
+
+    const isNumber = isNumeric(key);
+
+    if (isNumber) {
+      key = toNumberKey(key);
+    }
+
+    if (key.length > 1) {
+      key = sanitize(key, {
+        whitespace: '_',
+        underscore: true,
+        dash: true,
+        special: true,
+      });
+    }
+
+    return (
+      acc +
+      `  ${keyword.isIdentifierNameES5(key) ? key : `'${key}'`}= ${val},\n`
+    );
+  }, '');
+};
+
 const toNumberKey = (value: string) => {
   if (value[0] === '-') {
     return `NUMBER_MINUS_${value.slice(1)}`;

packages/core/src/getters/query-params.ts

@@ -68,11 +68,11 @@ const getQueryParamsTypes = (
 
     if (resolvedValue.isEnum && !resolvedValue.isRef) {
       const enumName = queryName;
-
       const enumValue = getEnum(
         resolvedValue.value,
         enumName,
         resolvedValue.originalSchema?.['x-enumNames'],
+        context.override.useNativeEnums,
       );
 
       return {

packages/core/src/resolvers/object.ts

@@ -52,6 +52,7 @@ export const resolveObject = ({
       resolvedValue.value,
       propName,
       resolvedValue.originalSchema?.['x-enumNames'],
+      context.override.useNativeEnums,
     );
 
     return {

packages/core/src/types.ts

@@ -111,6 +111,7 @@ export type NormalizedOverrideOutput = {
   useDeprecatedOperations?: boolean;
   useBigInt?: boolean;
   useNamedParameters?: boolean;
+  useNativeEnums?: boolean;
 };
 
 export type NormalizedMutator = {
@@ -302,6 +303,7 @@ export type OverrideOutput = {
   useDeprecatedOperations?: boolean;
   useBigInt?: boolean;
   useNamedParameters?: boolean;
+  useNativeEnums?: boolean;
 };
 
 export type OverrideOutputContentType = {

packages/orval/src/utils/options.ts

@@ -199,6 +199,7 @@ export const normalizeOptions = async (
         useDates: outputOptions.override?.useDates || false,
         useDeprecatedOperations:
           outputOptions.override?.useDeprecatedOperations ?? true,
+        useNativeEnums: outputOptions.override?.useNativeEnums ?? false,
       },
     },
     hooks: options.hooks ? normalizeHooks(options.hooks) : {},