Typescript

TypeScript Code Style

Strict, opinionated rules. Follow these to write correct code on the first draft.

Control Flow

• Early returns for guard clauses — return early for error/edge cases to keep main logic flat
• Always use block bodies for if with return — never if (!x) return; on one line
• Prefer positive conditions — check what should happen, not what shouldn't. Does NOT apply to guard clauses, where negative checks are expected
• No else after return — if a branch returns, the next block needs no else
• switch over chained if — when checking the same variable against multiple values

Type Safety

• No any — forbidden. Use unknown for uncertain types, generics to preserve/relate types
• No non-null assertions (!) — forbidden. Use optional chaining (?.) or guard clauses
• Minimize as casting — fix types at the source. Use generics, satisfies, or type guards instead
• Generics over broad types — prefer generic parameters over accepting broad types and casting results
• Let TypeScript infer return types — only annotate when needed (public APIs, recursion, or when inference produces the wrong type)

Enums

No enums — forbidden. Use as const objects with derived types:

const Status = {
  Active: 'active',
  Inactive: 'inactive',
} as const;

type Status = (typeof Status)[keyof typeof Status];

Naming

• Be descriptive — prefer specificity over brevity. activeUsers not data, sortByDate not process
• No I/T prefixes — User not IUser, Config not TConfig

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