typescript-coding-standards

Set "strict": true in tsconfig.json compilerOptions, which enables noImplicitAny, strictNullChecks, strictFunctionTypes, and related checks. The provided tsconfig.strict.json also adds noUncheckedIndexedAccess and noImplicitOverride for stronger safety.

Branded types intersect a primitive with a unique brand property, creating distinct types like UserId versus ProductId that cannot be mixed at compile time. Use them for entity IDs, currencies, and validated strings where primitive values carry different semantics.

Use unknown for truly dynamic data because it forces type narrowing before use, while any disables type checking entirely. The standards prohibit any via the @typescript-eslint/no-explicit-any ESLint rule.

Use a discriminated union Result type with success and failure variants, plus custom Error subclasses carrying context like field names or operation codes. A tryCatch wrapper converts rejected promises into Result values for consistent handling.

Yes, the configuration sets parserOptions.project to tsconfig.json, enabling type-aware rules like no-floating-promises and no-misused-promises from @typescript-eslint. It also integrates import ordering, promise rules, and security checks.

Branded types exist only at compile time and are erased after compilation, so they provide zero runtime validation. Factory functions like createUserId must perform runtime checks, and values can still be forged with explicit type assertions.