How can I validate data in TypeScript?

How can I validate data in TypeScript?

You can validate data in TypeScript using various methods like type guards, interfaces, and libraries like Joi or Yup.

Can you show me an example using a type guard?

Sure! Here's a simple type guard example:

function isString(value: any): value is string {
    return typeof value === 'string';
}

const input: any = 'Hello';
if (isString(input)) {
    console.log('Input is a string:', input);
} else {
    console.log('Input is not a string.');
}

What about using a library like Yup?

With Yup, you can define a schema for validation. Here's an example:

import * as Yup from 'yup';

const schema = Yup.object().shape({
    name: Yup.string().required(),
    age: Yup.number().positive().integer().required(),
});

schema.validate({ name: 'John', age: 30 })
    .then(() => console.log('Validation succeeded!'))
    .catch(err => console.log('Validation failed:', err.errors));