Function: negateGuard()

API / @xmachines/play-xstate / negateGuard

function negateGuard<TContext, TEvent>(guard): ComposedGuard;

Defined in: packages/play-xstate/src/guards/compose.ts:215

Negates a guard, through the not() helper of XState

The function inverts the result of a guard: the guard passes, and NOT then fails; the guard fails, and NOT then passes. It uses the built-in not() helper of XState, and the serialization is therefore correct.

Type Parameters

Type Parameter	Default type	Description
`TContext`	`any`	The context type of the state machine
`TEvent`	`any`	The event type

Parameters

Parameter	Type	Description
`guard`	`string` \| `Guard`<`TContext`, `TEvent`>	The guard predicate to negate, or its name

Returns

ComposedGuard

The not() guard negation of XState

Example

A NOT composition with a named guard

import { setup } from "xstate";
import { negateGuard } from "@xmachines/play-xstate";

const machine = setup({
  guards: {
    isGuest: ({ context }) => !context.userId,
  },
}).createMachine({
  on: {
    accessDashboard: {
      // Permit the transition when the user is NOT a guest, which means an authenticated user
      guard: negateGuard("isGuest"),
      target: "dashboard",
    },
  },
});

See

composeGuards for the AND composition
composeGuardsOr for the OR composition

Deprecated

Use the and(), or(), and not() combinators of XState directly. This helper does not compose with a guard slot that setup() types, and the next major version removes it.