TypeScript · Type Alias

any

any opts a value out of TypeScript’s static checking, allowing broad assignments and unchecked property access. It helps bridge untyped JavaScript or dependencies, but sacrifices type safety and should be tightly contained.

How it works

The any type opts a value out of TypeScript's normal checking. It can accept or produce arbitrary values and permits unchecked property access, which is useful while integrating untyped JavaScript but removes safety at that boundary.

Syntax

let value: any;
const result: any = expression;

Key points

Annotate a value as any when deliberately opting out of checking at an untyped integration point.
It can ease incremental migration when existing JavaScript or a dependency lacks useful type information.
Property reads and function calls through any are not verified for existence or signature compatibility.

Common mistakes

Do not treat any as a safer form of unknown: nonexistent properties and calls are permitted without validation.
Using any broadly defeats the checking that TypeScript is intended to provide; keep it limited to necessary boundaries.

Example: An untyped boundary

declare function getValue(key: string): any;

const value: any = getValue("user");
const label: string = value.label;
value.missingMethod();

The declaration represents an untyped boundary; arbitrary property access and assignment compile, so validate or narrow the value before relying on it.

When to use it

Untyped dependencies

Integrating JavaScript modules or third-party packages without usable declarations.

Gradual adoption

Migrating a JavaScript codebase incrementally while adding types around stable areas.

Controlled migration boundary

Representing a deliberate, temporary escape hatch during a staged refactor.

Interview questions

QWhat does any do in TypeScript?

any is an escape hatch from static checking. Expressions with this type can be assigned broadly and can use arbitrary properties or calls without the compiler verifying them.

Follow-up: How does unknown differ? unknown accepts values from any source, but consumers must narrow or validate it before using it.

QWhen might using any be justified?

It is useful at boundaries such as JavaScript code or third-party libraries whose types are unavailable. This supports gradual adoption of TypeScript, but the unchecked boundary should be kept small.

Follow-up: How would you contain it? Return unknown from the boundary, validate the runtime shape, and expose a precise type to the rest of the codebase.

QHow can a large codebase detect implicit any values?

An explicit annotation records an intentional opt-out, while an implicit any can arise where TypeScript cannot infer a type. The noImplicitAny compiler option reports the latter.

Follow-up: What broader setting enables that check? The strict option includes the relevant strictness checks, including implicit-any detection.

unknown
noImplicitAny
strict
type safety

Source: Documentation - The Basics - TypeScript. Checked 2026-10-15.

any