Skip to main content

⚡ Quick Start

Get up and running with Seal in just 5 minutes! This guide will walk you through the essential concepts and get you validating data right away.

Your First Validation​

import { v } from "@warlock.js/seal";

// 1. Define a schema
const userSchema = v.object({
  name: v.string().required().minLength(2),
  email: v.string().email().required(),
  age: v.int().min(18).max(120),
});

// 2. Validate data
const result = await v.validate(userSchema, {
  name: "John Doe",
  email: "john@example.com",
  age: 25,
});

// 3. Check the result
if (result.isValid) {
  console.log("✅ Valid data:", result.data);
} else {
  console.log("❌ Validation errors:", result.errors);
}

Understanding Results​

The validate function returns a ValidationResult:

interface ValidationResult {
  isValid: boolean;
  data: any; // The validated (and potentially mutated) data
  errors: ValidationError[]; // Array of validation errors
}

Common Validators​

String Validation​

const emailSchema = v.string()
  .required()
  .trim()           // Remove whitespace
  .lowercase()      // Convert to lowercase
  .email()          // Validate email format
  .maxLength(100);  // Check length

Number Validation​

const ageSchema = v.int()
  .required()
  .between(18, 120); // Age between 18 and 120

Array Validation​

const tagsSchema = v.array(v.string())
  .minLength(1)     // At least 1 tag
  .maxLength(10)    // At most 10 tags
  .unique();        // All tags must be unique

Data Transformation​

Seal can transform your data during validation:

const schema = v.object({
  name: v.string()
    .trim()           // Remove whitespace
    .capitalize(),    // Capitalize first letter
  email: v.string()
    .lowercase()      // Convert to lowercase
    .email(),         // Validate email
});

const result = await v.validate(schema, {
  name: "  john doe  ",
  email: "JOHN@EXAMPLE.COM",
});

console.log(result.data);
// Output: { name: "John doe", email: "john@example.com" }

TypeScript Integration​

Get full type safety:

import { v, type Infer } from "@warlock.js/seal";

const userSchema = v.object({
  name: v.string().required(),
  email: v.string().email().required(),
  age: v.int().min(18),
});

// TypeScript infers the exact type!
type User = Infer<typeof userSchema>;
// User = { name: string; email: string; age: number }

Error Handling​

Handle validation errors gracefully:

const result = await v.validate(schema, invalidData);

if (!result.isValid) {
  result.errors.forEach((error) => {
    console.log(`❌ ${error.input}: ${error.error}`);
  });
}

What's Next?​

Now that you understand the basics, explore these topics:

Ready to dive deeper? Let's explore the core concepts! 🚀