invariantfunction invariant(value: boolean, message?: string): asserts value;function invariant<T>(value: T | null | undefined, message?: string): asserts value is T;§invariant(value: boolean, message?: string): asserts value[src]§Parameters§value: boolean[src]§message?: string optional[src]§Return Type§asserts value[src]§invariant<T>(value: T | null | undefined, message?: string): asserts value is T[src]§Type Parameters§T[src]§Parameters§value: T | null | undefined[src]§message?: string optional[src]§Return Type§asserts value is T[src]