Yup Validator, nodeJS, and Javascript Library

Here's an explanation of Yup Validator for Node.js, with 10 code examples

Yup: A Powerful Validation Library

Yup is a popular Node.js library that makes data validation both straightforward and flexible. It offers a fluent API for defining validation schemas, ensuring that data adheres to your defined rules before being processed by your application.

Key Features:

• Schema-Based Validation: Define validation rules using a clear schema structure.

• Concise and Expressive API: Chain validation methods for a readable and intuitive syntax.

• TypeScript Support: Strong typing for enhanced code reliability.

• Asynchronous Validation: Handle validation tasks that involve asynchronous operations.

• Custom Validation: Create custom validation functions for specific requirements.

• Error Handling: Provides informative error messages for debugging and user feedback.

• Integration with Frameworks: Works seamlessly with frameworks like Express.js and React.

Code Examples:

1. Basic String Validation:

const yup = require('yup');

const nameSchema = yup.string().required('Name is required');

try {
  const validatedName = await nameSchema.validate('John Doe');
  console.log(validatedName); // Output: "John Doe"
} catch (error) {
  console.error(error.message);
}

1. Number Validation:

const ageSchema = yup.number().required().positive().integer();

1. Mixed Type Validation:

const userSchema = yup.object().shape({
  name: nameSchema,
  age: ageSchema,
  email: yup.string().email('Invalid email format'),
});

1. Array Validation:

const itemsSchema = yup.array().of(yup.string().required());

1. Custom Validation:

const isStrongPassword = (password) => password.length >= 8;

const passwordSchema = yup.string().required().test(
  'isStrongPassword',
  'Password must be at least 8 characters long',
  isStrongPassword
);

1. Asynchronous Validation:

const uniqueEmail = async (email) => {
  // Check email uniqueness in a database
};

const emailSchema = yup.string().email().test(
  'uniqueEmail',
  'Email already exists',
  uniqueEmail
);

1. Conditional Validation:

const addressSchema = yup.object().shape({
  street: yup.string().required('Street is required'),
  city: yup.string().required('City is required'),
  state: yup.string().when('country', {
    is: 'US',
    then: yup.string().required('State is required for US residents'),
    otherwise: yup.string(),
  }),
});

1. Integration with Frameworks:

// Express.js example
const express = require('express');
const app = express();

app.post('/user', async (req, res) => {
  try {
    await userSchema.validate(req.body);
    // Process valid user data
  } catch (error) {
    res.status(400).json({ errors: error.message });
  }
});

1. Custom Error Messages:

const emailSchema = yup.string().email('Invalid email format').required('Email is required');

1. Combining Validators:

const passwordSchema = yup.string()
  .required('Password is required')
  .min(8, 'Password must be at least 8 characters long')
  .max(32, 'Password must be at most 32 characters long')
  .matches(/[a-z]/, 'Password must contain a lowercase letter')
  .matches(/[A-Z]/, 'Password must contain an uppercase letter')
  .matches(/\d/, 'Password must contain a number')
  .matches(/[^a-zA-Z\d]/, 'Password must contain a special character');

If you're looking for the official site for the Yup validation library for Node.js, the main website is actually the GitHub repository: https://github.com/jquense/yup. The repository contains comprehensive documentation, tutorials, and examples alongside the source code. While there is no dedicated website specifically for Yup as a standalone product, the GitHub repository serves as the official source of information.

Yup is a versatile tool that can greatly improve the robustness and accuracy of your Node.js applications. Give it a try and see how it simplifies your data validation tasks!