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# isSupportedChain

Type guard that checks whether a chain ID is supported.

## Import

```ts twoslash
import { isSupportedChain } from '@railnetorg/railnet-sdk'
```

## Usage

```ts twoslash
import { isSupportedChain, getAddresses } from '@railnetorg/railnet-sdk'

const chainId: number = 8453

if (isSupportedChain(chainId)) {
  const addresses = getAddresses(chainId)
}
```

## Returns

`chainId is SupportedChainId`. Narrows the type in a conditional.

Returns `true` if the chain ID has protocol addresses configured, `false` otherwise. This checks
production deployments only; a chain with a [staging](/contracts/staging) deployment but no
production one, such as Base (`8453`), returns `false` here.

## Parameters

### chainId

* **Type:** `number`