# isFtSigner · FT4 TypeScript client · Chromia Docs (concept)

> isFtSigner(signer: Signer ): signer is FtSigner Type assertion function that checks if the specified signer is an FtSigner Parameters signer: Signer the si

Source: https://docs.chromia.com/pages/ft4-ts-client/functions/authentication.isFtSigner/

Function

# isFtSigner

* ```signature
  isFtSigner(signer: Signer): signer is FtSigner
  ```

  Type assertion function that checks if the specified signer is an `FtSigner`

  #### Parameters

  + signer: [Signer](https://docs.chromia.com/pages/ft4-ts-client/types/authentication.Signer/)

    the signer to check

  #### Returns signer is [FtSigner](https://docs.chromia.com/pages/ft4-ts-client/interfaces/authentication.FtSigner/)

  true if the specified signer was an `FtSigner`. Else false.

[View this page on docs.chromia.com](https://docs.chromia.com/pages/ft4-ts-client/functions/authentication.isFtSigner.html)Generated API reference, mirrored from the live docs