Guided Notes

Functions & Types

Typing parameters and return values, optional, default and rest parameters, function type aliases, callbacks, and overloads.

Parameters and return types

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function vat(net: number, rate: number = 0.18): number { return net * rate; }

• Parameters need types (TypeScript can't infer them in a declaration). • Return types can be inferred, but annotating exported functions documents intent and catches accidental changes. • Calling with the wrong number or type of arguments is an error.

← Union, Intersection & Literal Types