Snippets, observations, and things worth keeping.
§ Notes · 2026-04-22
Use satisfies to validate a value's shape without widening it.
1 min read
as casts a value, throwing away whatever the compiler knew. satisfies validates a value against a type and keeps the narrower inferred shape:
Reach for satisfies whenever you'd otherwise write as const plus a manual type assertion.
type Color = 'gold' | 'crimson';
const palette = {
gold: 'oklch(0.74 0.105 72)',
crimson: 'oklch(0.55 0.180 22)',
} satisfies Record<Color, string>;
type Keys = keyof typeof palette; // 'gold' | 'crimson' (kept narrow)