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

> relativeBlockHeight(value: number): RuleVariableValue < LoginConfigRuleVariable > Creates a login config rule variable of type relative block height
which 

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

Function

# relativeBlockHeight

* ```signature
  relativeBlockHeight(value: number): RuleVariableValue<LoginConfigRuleVariable>
  ```

  Creates a login config rule variable of type relative block height
  which will expire after `value` number of blocks after this was registered.

  #### Parameters

  + value: number

    after how many blocks this rule should expire

  #### Returns [RuleVariableValue](https://docs.chromia.com/pages/ft4-ts-client/types/accounts.RuleVariableValue/)<[LoginConfigRuleVariable](https://docs.chromia.com/pages/ft4-ts-client/types/authentication.LoginConfigRuleVariable/)>

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