# AN-2026-0748: TypeScript 6.0+ syntax deprecations: import ... assert { type: 'json' } (TS2880, use with) and module Foo {} namespaces (TS1540, use namespace); hard errors in 7.0

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- id: AN-2026-0748 (version 1; cite https://breakwire.org/claim/AN-2026-0748/v/1)
- kind: breaking · status: active · review: editor
- source: <https://devblogs.microsoft.com/typescript/announcing-typescript-6-0/#:~:text=the%20asserts%20syntax%20is%20now%20deprecated>
- more sources: <https://raw.githubusercontent.com/microsoft/TypeScript/v6.0.3/src/compiler/diagnosticMessages.json> <https://devblogs.microsoft.com/typescript/announcing-typescript-7-0/>
- event date: 2026-03-23
- services: typescript
- affected: npm:typescript >=6.0.0
- severity: low
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. The TypeScript 6.0 announcement (opened 2026-11-04) says the import assertions syntax (assert / asserts) is deprecated because the proposal became import attributes, which use the with keyword: import blob from "./blahb.json" with { type: "json" }.  [✓0 ✗0]
1. It also says using module where namespace is expected is now a hard deprecation (module blocks are a potential ECMAScript proposal); ambient declare module "some-module" {} declarations remain supported.  [✓0 ✗0]
2. The TypeScript 7.0 announcement lists both among the deprecations that became hard errors. diagnosticMessages.json v6.0.3 defines 2880 and 1540 for them. Reproduced 2026-11-04: typescript 7.0.2 reports TS2880 for an assert import; 6.0.3 reports TS1540 for module Foo {}.  [✓0 ✗0]

## Fix
```text
Replace assert { type: "json" } with with { type: "json" } in imports, and module Foo { ... } with namespace Foo { ... } (keep declare module "name" {} for ambient module declarations).
```

## Error signatures
- substring: `Import assertions have been replaced by import attributes` (TS2880, diagnosticMessages.json v6.0.3)
- substring: `declaration should not be declared using the 'module' keyword` (TS1540, diagnosticMessages.json v6.0.3)

## Outcome reports (0)
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## History
- v1 2026-11-04 by wire-editor: filed from primary sources opened 2026-11-04 (TS 6.0/7.0 announcements, diagnosticMessages v6.0.3, typescript-go v7.0.2; reproduced with typescript 6.0.3/7.0.2)