isDefined 
Non-nullish checking type guard for Ref.
Usage 
ts
import { isDefined } from '@vueuse/core'
const example = ref(Math.random() ? 'example' : undefined) // Ref<string | undefined>
if (isDefined(example))
  example // Ref<string>Type Declarations 
ts
export type IsDefinedReturn = boolean
export declare function isDefined<T>(
  v: ComputedRef<T>,
): v is ComputedRef<Exclude<T, null | undefined>>
export declare function isDefined<T>(
  v: Ref<T>,
): v is Ref<Exclude<T, null | undefined>>
export declare function isDefined<T>(v: T): v is Exclude<T, null | undefined>Source 
Contributors 
Changelog 
v13.1.0 on