---
title: Types
description: TypeScript type definitions for the Flagship binding, including Flagship, FlagshipEvaluationContext, and FlagshipEvaluationDetails.
image: https://developers.cloudflare.com/dev-products-preview.png
---

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# Types

The Flagship binding uses the following TypeScript types. These are available from the `@cloudflare/workers-types` package after running `npx wrangler types`.

## `Flagship`

The binding type. Each Flagship binding in your Wrangler configuration is typed as `Flagship` on the `Env` interface.

TypeScript

```
interface Env {  FLAGS: Flagship;}
```

Refer to the [methods reference](https://developers.cloudflare.com/flagship/binding/methods/) for the full list of evaluation methods available on the binding.

## `FlagshipEvaluationContext`

A record of attribute names to values passed for [targeting rules](https://developers.cloudflare.com/flagship/targeting/). Use this to provide user attributes such as user ID, country, or plan type.

TypeScript

```
type FlagshipEvaluationContext = Record<string, string | number | boolean>;
```

## `FlagshipEvaluationDetails`

Returned by the `*Details` methods. Contains the evaluated value and metadata about how Flagship resolved the flag.

TypeScript

```
interface FlagshipEvaluationDetails<T> {  flagKey: string;  value: T;  variant?: string;  reason?: string;  errorCode?: string;}
```

| Property  | Type   | Description                                                                         |
| --------- | ------ | ----------------------------------------------------------------------------------- |
| flagKey   | string | The key of the evaluated flag.                                                      |
| value     | T      | The resolved flag value.                                                            |
| variant   | string | The name of the matched variant, if any.                                            |
| reason    | string | Why the flag resolved to this value (for example, "TARGETING\_MATCH" or "DEFAULT"). |
| errorCode | string | An error code if evaluation failed (for example, "TYPE\_MISMATCH" or "GENERAL").    |

Refer to [evaluation reasons and error codes](https://developers.cloudflare.com/flagship/reference/evaluation-reasons/) for the full list of possible values.

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