Question 1

How to validate nested objects with fastest-validator?

Accepted Answer

Use the 'object' validator with nested 'props' to define the structure. For example, specify a schema with objects inside objects, and the library recursively validates each property based on the defined rules.

Question 2

fastest-validator vs Joi: which should I use?

Accepted Answer

fastest-validator is significantly faster due to schema compilation, making it ideal for performance-critical applications. However, Joi has a larger ecosystem and more built-in features, so choose based on speed vs. community support.

Question 3

How to add custom validation rules in fastest-validator?

Accepted Answer

Use the 'custom' type in your schema or register a custom validator via the 'add' method. Provide a function that checks the value and returns it, with error handling and optional sanitization capabilities.

Question 4

Does fastest-validator work with TypeScript?

Accepted Answer

The README shows usage with Deno and TypeScript via esm.sh, but for Node.js, you may need to check for separate type definitions. It likely supports TypeScript, but documentation on type inference is limited in the provided README.

Question 5

Can I use fastest-validator for React form validation?

Accepted Answer

Yes, it supports browser usage via a script tag or module import. Compile schemas to validate form inputs, but you'll need to integrate it with React state management, as it doesn't provide React-specific hooks out-of-the-box.

Question 6

How to handle async validation with fastest-validator?

Accepted Answer

Enable async mode by setting '$$async: true' in the schema and use custom validators that return Promises or async functions for checks like API calls or database queries, ensuring proper error handling.

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