The right-hand side of an 'instanceof' expression must be either of type 'any...
Production Risk
Build will fail; resolve before shipping.
A type-checking error (TS2359): The right-hand side of an 'instanceof' expression must be either of type 'any', a class, function, or other type assignable to the 'Function' interface type, or an object type with a 'Symbol.hasInstance' method.. This diagnostic is emitted by the TypeScript compiler when the right-hand side of an 'instanceof' expression must be either of type 'any', a class, function, or other type assignable to the 'Function' interface type, or an object type with a 'Symbol.hasInstance' method..
- 1Incorrect TypeScript syntax or type usage
- 2Type mismatch between declared and actual value
TypeScript compiler reports TS2359 during type checking.
// Triggers TS2359 // The right-hand side of an 'instanceof' expression must be either of type 'any', a class, function, or other type assignable to the 'Function' interface type, or an object type with a 'Symbol.hasInstance' method.
expected output
error TS2359: The right-hand side of an 'instanceof' expression must be either of type 'any', a class, function, or other type assignable to the 'Function' interface type, or an object type with a 'Symbol.hasInstance' method.
Fix
Address the TypeScript diagnostic
WHEN When this error is reported by the compiler
// Run the TypeScript compiler for details: npx tsc --noEmit // Use the TypeScript playground to test your code: // https://www.typescriptlang.org/play
Why this works
Review the full error message and location; the TypeScript handbook provides guidance on each error category.
✕ Suppress with @ts-ignore instead of fixing the type
ts-ignore hides real type errors and makes refactoring unsafe.
TypeScript Compiler Diagnostics
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