assert

Asserts a condition. This function can be used as a assertion function in TypeScript.

function assert(
  // Condition to assert
  condition: unknown,
  // The error to throw when `condition` is `false`
  // If string is given, it wraps it with `new Error()`.
  // @default new Error()
  error: Error | string
): asserts condition;

Examples

let accountId: string | null;

assert(accountId != null, new Error('No "accountId"'));

accountId; // string (type guarded)