How do I use a validation library in my project?

How do I use a validation library in my project?

Using a validation library typically involves installing it via a package manager, then importing it into your project. Which library are you considering?

I'm thinking about using Joi for validating user input.

Great choice! To use Joi, first install it using npm: npm install joi. Then, you can create a schema to define your validation rules.

Can you show me an example of a schema?

Sure! Here's a simple example:

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}$')).required(),
});

This schema validates a username and password.

How do I validate data against this schema?

You can use the validate method provided by Joi. For example:

const { error, value } = schema.validate({ username: 'abc', password: '123' });
if (error) {
  console.log('Validation failed:', error.details);
} else {
  console.log('Validation succeeded:', value);
}