typescript-functions

Functions

Apply the TypeScript Style Guide's function conventions in the context of the current task.

Workflow

1. Inspect the consuming repository's conventions and configuration.
2. Let explicit repository conventions take precedence over this opinionated guidance.
3. Apply, review, or explain only the guidance relevant to the task.
4. State important tradeoffs when the appropriate design depends on context or judgment.

Boundaries

• Keep TypeScript and ESLint responsible for checks they can enforce automatically.
• Do not introduce unrelated TypeScript Style Guide conventions merely because this skill is active.

Related Guidance

Function Arguments

For detailed guidance on mutually exclusive function arguments, use typescript-discriminated-unions when it is available.

Functions

Function conventions should be followed as much as possible (some derive from basic functional programming concepts):

General

Prefer functions that:

• have a single responsibility.
• make dependencies explicit through arguments.
• return a value when they calculate or transform data.
• avoid side effects when practical.

A stateless function does not retain data between calls. A deterministic function returns the same result for the same inputs. A pure function is deterministic and has no observable side effects, making it easier to understand, test, and reuse.

Not every function can be pure. Network requests, storage, logging, and UI updates require side effects. Keep these functions small and isolate side effects from pure business logic.

Single Object Arg

When a function accepts several related parameters, prefer a single object parameter. Named properties make call sites easier to understand and allow the function API to evolve without relying on argument order.

Keep positional parameters when their meaning and order are obvious, or when a conventional signature is clearer, such as isNumber(value) or a callback.