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Jest · Matcher

toBeInstanceOf

.toBeInstanceOf(Class) checks whether a value is an instance of a given class or constructor. It uses JavaScript's instanceof behavior.

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Syntax

expect(received).toBeInstanceOf(Class)

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  • expect(value)
  • toBe
  • toBeNull
  • toBeDefined
  • toBeInstanceOf

Source: Expect · Jest. Checked 2026-11-03.