Schema - Function

The .function method is used to validate whether a given value is of type function. It ensures that the input is a valid function, making it useful for validating function-type data such as event handlers, callbacks, or any other function-based logic in your application.

This method is crucial when you need strict type validation, ensuring that only valid functions are allowed.

Content

• Quick Start
• Error Messages
  • Default Error Message
  • Custom Error Messages

Quick Start

Below is an example of how to use .function to validate whether a value is a valid function:

import { schema } from 'vkrun'
 
const schemaValidation = schema().function()
 
const validateA = schemaValidation.validate(() => {}) // Valid function
const validateB = schemaValidation.validate('test') // Invalid, string is not a function
 
console.log(validateA) // true
console.log(validateB) // false

Error Messages

The .function method provides robust error messages to help identify issues during validation. These messages can be used as is or customized for specific use cases.

Default Error Message

If no custom error message is provided, the .function method generates the following default message:

"[valueName] must be a function type!"

This message dynamically replaces [valueName] with the name of the variable being validated, providing clarity about the source of the error.

Example

import { schema } from 'vkrun'
 
const value = 'test'
 
const schemaValidation = schema().function()
 
const defaultResult = schemaValidation.parse(value, 'function_value')

Throw:

function_value must be a function type!

Custom Error Messages

To make error messages more descriptive or tailored to specific use cases, you can define custom messages using keywords like [value] and [valueName]. These keywords are replaced dynamically with the actual value and the name of the variable being validated.

Supported Keywords

• [value]: The actual value being validated.
• [valueName]: The name of the value being validated.

Example

import { schema } from 'vkrun'
 
const value = 'test'
 
const schemaValidation = schema().function({
	message: '[valueName] must be of type function, but received [value]!',
})
 
const customResult = schemaValidation.parse(value, 'function_value')

Throw:

function_value must be of type function, but received test!