Strategy Pattern — Switching behavior at runtime

Encapsulate algorithms behind a shared interface so you can swap behavior without branching logic.

Example (TypeScript)

type PricingStrategy = (base: number) => number;

const standard: PricingStrategy = (base) => base;
const discounted = (pct: number): PricingStrategy => (base) => base * (1 - pct);

const quote = (base: number, strategy: PricingStrategy) => strategy(base);

quote(100, standard);
quote(100, discounted(0.2));

Why it matters

• Avoids if/else trees for feature variants.
• Encourages testable, focused behavior units.
• Lets you inject behavior based on config or runtime data.

Questions & Answers