@types/joi

What is @types/joi?

@types/joi provides TypeScript type definitions for the Joi validation library, which is used to validate JavaScript objects and data structures.

What are @types/joi's main functionalities?

Basic Validation

This feature allows you to define a schema and validate an object against it. The schema can include various rules such as string patterns, number ranges, and required fields.

const Joi = require('joi');

const schema = Joi.object({
  username: Joi.string().alphanum().min(3).max(30).required(),
  password: Joi.string().pattern(new RegExp('^[a-zA-Z0-9]{3,30}$')),
  birth_year: Joi.number().integer().min(1900).max(2013)
});

const { error, value } = schema.validate({ username: 'abc', birth_year: 1994 });

Custom Error Messages

This feature allows you to customize error messages for specific validation rules, making it easier to provide user-friendly feedback.

const schema = Joi.object({
  username: Joi.string().min(3).message('Username must be at least 3 characters long')
});

const { error, value } = schema.validate({ username: 'ab' });
if (error) {
  console.log(error.details[0].message); // 'Username must be at least 3 characters long'
}

Nested Object Validation

This feature allows you to validate nested objects, ensuring that all required fields within the nested structure are present and valid.

const schema = Joi.object({
  user: Joi.object({
    username: Joi.string().required(),
    password: Joi.string().required()
  }).required()
});

const { error, value } = schema.validate({ user: { username: 'abc', password: '123' } });

Array Validation

This feature allows you to validate arrays, including the types of items within the array and constraints on the array itself, such as minimum length.

const schema = Joi.object({
  tags: Joi.array().items(Joi.string().min(2)).min(1).required()
});

const { error, value } = schema.validate({ tags: ['node', 'express'] });

Other packages similar to @types/joi

yup

Yup is a JavaScript schema builder for value parsing and validation. It is similar to Joi but is often considered more lightweight and has a more modern API. Yup also integrates well with React and Formik for form validation.

ajv

AJV (Another JSON Schema Validator) is a JSON schema validator that is very fast and supports JSON Schema draft-07. It is more focused on JSON schema validation and is often used in applications where performance is critical.

validator

Validator is a library of string validators and sanitizers. It is less comprehensive than Joi but is very useful for simple string validation tasks. It is often used in conjunction with other validation libraries.

README

This is a stub types definition for @types/joi (https://github.com/sideway/joi#readme).

joi provides its own type definitions, so you don't need @types/joi installed!