# isUndefined

# Function: isUndefined()

```ts
function isUndefined(value): BasicExpression<boolean>;
```

Defined in: [packages/db/src/query/builder/functions.ts:247](https://github.com/TanStack/db/blob/main/packages/db/src/query/builder/functions.ts#L247)

## Parameters

### value

`ExpressionLike`

## Returns

[`BasicExpression`](../@tanstack/namespaces/IR/type-aliases/BasicExpression.md)\<`boolean`\>