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# Function

## Docs

- [Function overview](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/function-overview.md): Functions are user-defined JavaScript code snippets to ensure data integrity and drive automation in your business use cases, such as validating data format or performing complex calculations.
- [Function format](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/function-format.md): Introduces the format and best practices of using functions.
- [Format of validation functions](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/function-format/format-of-validation-functions.md): Describes the format of validation functions, such as function syntax, parameters, and return values.
- [Format of formula functions](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/function-format/format-of-formula-functions.md): Describes the format of formula functions, such as function syntax, parameters, and return values.
- [Create a function from scratch](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/function-management/create-a-function-from-scratch.md): Learn how to create a function from scratch.
- [Create a function from templates](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/function-management/create-a-function-from-templates.md): Learn how to create a function from built-in templates.
- [Update a function](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/function-management/update-a-function.md): Learn how to update a function.
- [Activate a function](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/function-management/activate-a-function.md): Learn how to activate a function that is in the Draft or Inactive status.
- [Delete a function](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/function-management/delete-a-function.md): Learn how to delete a function.
- [Test a function](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/function-management/test-a-function.md): Learn how to test a function when creating or updating it.
- [Validation function use cases](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/use-cases-and-code-samples/validation-function-use-cases.md): Common use cases and code samples of validation function.
- [Formula function use cases](https://zuora.ferndocs.com/docs/platform/extensibility/custom-logic/function/use-cases-and-code-samples/formula-function-use-cases.md): Common use cases and code samples of formula function.