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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Preserve computed property in `--isolatedDeclarations` emit","articleBody":"### 🔍 Search Terms\n\nisolated declarations, computed properties\n\n### ✅ Viability Checklist\n\n- [x] This wouldn't be a breaking change in existing TypeScript/JavaScript code\n- [x] This wouldn't change the runtime behavior of existing JavaScript code\n- [x] This could be implemented without emitting different JS based on the types of the expressions\n- [x] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)\n- [x] This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types\n- [x] This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals\n\n### ⭐ Suggestion\n\nNow that #60052 allows for (some) computed properties in in `.d.ts` files I think the next step is for `--isolatedDeclaration` to be updated to not error and to emit the computed properties. Opening this issue if helpful to track this work.\n\nI believe the previous plan (#58800) to introduce a new syntactic marker is no longer required.\n\nRelated issues: #58533 #60818 #61068\n\n### 📃 Motivating Example\n\n```ts\nexport const prop: unique symbol = Symbol();\n\nexport class MyClass {\n    [prop] = () =\u003e Math.random();\n}\n```\n\n### `@isolatedDeclarations: false`\n\n[playground](https://www.typescriptlang.org/play/?isolatedDeclarations=false\u0026ts=5.8.3#code/PTAEAEEsGcHsBsCGAXApgEwCKoMZIE4qSwB20AXKAGaLzSoBQqAHgA6z7Kg6nRev5YrSgFcSkAI4jUoaAE8AtgCMEoALygAyopXwAFAEoA3AyZsOXPImjRQAWTkBhJDdABvBqC+gA2gKEAuuqghuoAfPYoABYAdIQk6LAKhiYAvgxAA)\n\n```ts\nexport declare const prop: unique symbol;\nexport declare class MyClass {\n    [prop]: () =\u003e number;\n}\n```\n\n### `@isolatedDeclarations: true` (current 🙁)\n\n[playground](https://www.typescriptlang.org/play/?isolatedDeclarations=true\u0026ts=5.8.3#code/PTAEAEEsGcHsBsCGAXApgEwCKoMZIE4qSwB20AXKMvgK6oBQqAHgA6z7Kg6nScv6wWlGiUgBHOqGgBPALYAjBKAC8oAMpzF8ABQBKANz1GrdpzyJo0UAFlpAYSSXQAb3qh3oANr9BAXRWgeioAfDYoABYAdIQk6LCyeoYAvvRAA)\n\n```sh\nts(9038) Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.\n```\n\n```ts\nexport declare const prop: unique symbol;\nexport declare class MyClass {\n}\n```\n\n### `@isolatedDeclarations: true` (future 🚀 )\n\nNo error and same emit as `@isolatedDeclarations: false`\n\n```ts\nexport declare const prop: unique symbol;\nexport declare class MyClass {\n    [prop]: () =\u003e number;\n}\n```\n\n### 💻 Use Cases\n\nThe primary use case is enabling isolated declarations at scale on large codebases that make heavy use of computed properties.\n","author":{"url":"https://github.com/acutmore","@type":"Person","name":"acutmore"},"datePublished":"2025-06-18T14:05:31.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":6},"url":"https://github.com/61892/TypeScript/issues/61892"}