Agent skill
yup
Validate data with Yup schemas. Use when adding form validation, defining API request schemas, validating configuration, or building type-safe validation pipelines in JavaScript/TypeScript.
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/yup
Metadata
Additional technical details for this skill
- tags
-
yup validation schema forms typescript
- author
- terminal-skills
- version
- 1.0.0
- category
- development
SKILL.md
Yup
Overview
Yup is a schema validation library for JavaScript. Define schemas declaratively, validate data, and get detailed error messages. Works with Formik, react-hook-form, and standalone. TypeScript-first with type inference.
Instructions
Step 1: Schemas
import * as yup from 'yup'
const userSchema = yup.object({
name: yup.string().min(2).max(100).required(),
email: yup.string().email().required(),
age: yup.number().positive().integer().min(13).max(120),
role: yup.string().oneOf(['admin', 'member', 'viewer']).default('member'),
tags: yup.array().of(yup.string()).min(1).max(10),
address: yup.object({
street: yup.string().required(),
city: yup.string().required(),
zip: yup.string().matches(/^\d{5}$/, 'Must be 5 digits'),
}),
})
// Validate
const user = await userSchema.validate(data, { abortEarly: false })
// Type inference
type User = yup.InferType<typeof userSchema>
Step 2: Custom Validation
const passwordSchema = yup.string()
.min(8)
.matches(/[A-Z]/, 'Must contain uppercase')
.matches(/[0-9]/, 'Must contain number')
.matches(/[^A-Za-z0-9]/, 'Must contain special character')
const signupSchema = yup.object({
password: passwordSchema.required(),
confirmPassword: yup.string()
.oneOf([yup.ref('password')], 'Passwords must match')
.required(),
})
Step 3: Conditional Validation
const schema = yup.object({
contactMethod: yup.string().oneOf(['email', 'phone']).required(),
email: yup.string().when('contactMethod', {
is: 'email',
then: (s) => s.email().required('Email required when contact method is email'),
}),
phone: yup.string().when('contactMethod', {
is: 'phone',
then: (s) => s.matches(/^\+\d{10,15}$/).required('Phone required'),
}),
})
Guidelines
abortEarly: falsereturns all errors at once — better UX than one-at-a-time.- Use
InferTypeto derive TypeScript types from schemas — single source of truth. - For new projects, consider Zod instead — better TypeScript inference and ecosystem.
- Yup is still the standard for Formik integration.
.when()for conditional validation — fields required only in certain contexts.
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