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#advanced (4)

Cheat sheets (4)

Declaration Merging — Interfaces, Namespaces, Modules, Globals

Deep dive into TypeScript declaration merging — interface merging, namespace + class, namespace + function, module augmentation, global augmentation, and the Express Request pattern.
typescript declarations modules patterns advanced

infer Keyword — Extracting types from patterns

TypeScript's infer keyword declares a fresh type variable inside a conditional type, letting you pull a sub-type out of a matched shape. It powers ReturnType, Parameters, Awaited, and most advanced type extractors.
typescript types advanced language

Template Literal Types — String Algebra at the Type Level

Template literal types let TypeScript pattern-match and synthesize string types — covering Uppercase/Lowercase intrinsics, infer-based parsers (Split, Join, CamelCase), route-param extraction, JSON path keys, and typed i18n helpers.
typescript types advanced template-literals language

TypeScript Compiler API — Codegen, codemods, and AST walks

Drive the TypeScript compiler programmatically — parse SourceFiles, query the type checker, transform ASTs with the factory, and write codemods that scale across a monorepo.
typescript tooling advanced compiler codegen