as const

as const is a TypeScript feature that allows you to tell the compiler to infer the narrowest or most specific type possible for an expression. Instead of the compiler widening the type of a value to its general type (like inferring a string variable as string), as const makes the compiler infer the value as a constant type (like inferring a string variable as the specific string literal type "hello"). This is useful for creating immutable data structures or when you need the compiler to enforce the exact values allowed.