isDefined

v0.0.15testeddemo

Type-guard that checks whether a ref's (or plain value's) current value is neither `null` nor `undefined`, narrowing the source to its `NonNullable` form. Unwraps refs with a single `unref` — no extra reactivity or watchers are created, so it is a cheap synchronous check that is fully SSR-safe. For a reactive guard that tracks changes, use {@link useIsDefined}.

Source Tests

Examples

const user = ref<User | null>(null);
if (isDefined(user)) {
  // `user` is now narrowed to `Ref<User>`
  console.log(user.value.name);
}

const value = isDefined(maybeNumber) ? maybeNumber.value : 0;

Demo

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Signatures

export function isDefined<T>(value: ComputedRef<T>): value is ComputedRef<NonNullable<T>>;

export function isDefined<T>(value: Ref<T>): value is Ref<NonNullable<T>>;

export function isDefined<T>(value: T): value is NonNullable<T>;

Type Parameters

T

Parameters

Parameter	Type	Default	Description
`value`	`T \| Ref<T, T>`	—	The ref or value to test

Returns

boolean`true` when the unwrapped value is non-nullish