TS7013
TypeScriptERRORNotableStrictHIGH confidence

Construct signature, which lacks return-type annotation, implicitly has an 'a...

Production Risk

Build will fail; resolve before shipping.

What this means

A strict mode error (TS7013): Construct signature, which lacks return-type annotation, implicitly has an 'any' return type.. This diagnostic is emitted by the TypeScript compiler when construct signature, which lacks return-type annotation, implicitly has an 'any' return type..

Why it happens
  1. 1TypeScript cannot infer the type and defaults to 'any' with --noImplicitAny
  2. 2Missing type annotation or type parameter
How to reproduce

TypeScript compiler reports TS7013 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS7013
// Construct signature, which lacks return-type annotation, implicitly has an 'any' return type.

expected output

error TS7013: Construct signature, which lacks return-type annotation, implicitly has an 'any' return type.

Fix

Add an explicit type annotation

WHEN When TypeScript cannot infer the type

Add an explicit type annotation
// Before (implicit any)
function process(value) { return value; }
// After (explicit type)
function process(value: string): string { return value; }

Why this works

Adding explicit type annotations removes the implicit 'any' and enables full type checking.

What not to do

Suppress with @ts-ignore instead of fixing the type

ts-ignore hides real type errors and makes refactoring unsafe.

Sources
Official documentation ↗

TypeScript Compiler Diagnostics

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