trigger-frontend-updates:typescript@5.9.2

Author: jeremycolin

packages/frontend-updates-runner/updates/typescript@5.9.2.md

@@ -1 +1,60 @@
-# TypeScript 5.9.2
+## TypeScript 5.9.2
+
+### **Minimal and Updated `tsc --init`**
+
+The TypeScript compiler now generates a more streamlined `tsconfig.json` with better defaults: [details](https://devblogs.microsoft.com/typescript/announcing-typescript-5-9/#minimal-and-updated-tsc---init)
+
+### **Support for `import defer`**
+
+TypeScript 5.9 introduces support for ECMAScript's deferred module evaluation proposal using the new `import defer` syntax. This feature allows you to import a module without immediately executing the module and its dependencies, providing better control over when work and side-effects occur.
+
+**Key Benefits:**
+
+- Module evaluation is deferred until you access a property of the imported namespace
+- Only namespace imports are supported: `import defer * as feature from "./some-feature.js"`
+- Useful for conditionally loading modules with expensive initialization
+- Can improve startup performance by deferring module evaluation until needed
+
+**Usage Example:**
+
+```typescript
+import defer * as feature from "./some-feature.js";
+
+// No side effects have occurred yet
+// Module is only evaluated when accessing a property:
+console.log(feature.specialConstant); // Now side effects occur
+```
+
+**Limitations:**
+
+- Only works with `--module` modes `preserve` and `esnext`
+- Not transformed by TypeScript - requires runtime support or bundler transformation
+- Named imports and default imports are not supported
+
+### **Summary Descriptions in DOM APIs**
+
+TypeScript now includes summary descriptions for many DOM APIs based on MDN documentation, providing quick context without needing to visit external documentation.
+
+### **Expandable Hovers (Preview)**
+
+New preview feature that allows expanding quick info tooltips to see deeper type information with configurable maximum hover length.
+
+### **Performance Optimizations** with cache instantiations on mappers and file system optimizations
+
+### **Notable Behavioral Changes**: **lib.d.ts Changes**
+
+- `ArrayBuffer` is no longer a supertype of `TypedArray` types
+- May affect code using `Buffer` from Node.js with `ArrayBuffer` types
+- New error messages for type mismatches between `ArrayBufferLike` and `BufferSource`
+
+## **Migration Notes**
+
+- Review any code using `ArrayBuffer` with `TypedArray` or `Buffer` types
+- Consider updating `tsconfig.json` files to use new defaults
+- Test expandable hovers feature in your editor
+- Update hover length settings if needed
+
+## **Resources**
+
+- [TypeScript 5.9 Release Notes](https://devblogs.microsoft.com/typescript/announcing-typescript-5-9/)
+- [TypeScript Configuration Reference](https://www.typescriptlang.org/tsconfig/)