Validation Utilities

const userSchema = z.object({
  id: z.string(),
  name: z.string()
});
 
type User = z.infer<typeof userSchema>;
// { id: string; name: string }

const ageSchema = z.string().transform(Number);
type Age = z.output<typeof ageSchema>; // number

class User {}
const userSchema = z.instanceof(User);

const hexColor = z.custom<string>(val => {
  return /^#[0-9A-F]{6}$/i.test(val);
});

const fnSchema = z.function()
  .args(z.string(), z.number())
  .returns(z.boolean());

const withDefault = z.object({
  name: z.string().default('Anonymous'),
  age: z.number().optional()
});

const eventSchema = z.discriminatedUnion('type', [
  z.object({
    type: z.literal('click'),
    x: z.number(),
    y: z.number()
  }),
  z.object({
    type: z.literal('keypress'),
    key: z.string()
  })
]);

interface Category {
  name: string;
  subcategories: Category[];
}
 
const categorySchema: z.ZodType<Category> = z.lazy(() =>
  z.object({
    name: z.string(),
    subcategories: z.array(categorySchema)
  })
);

const coerceNumber = z.coerce.number(); // Converts strings to numbers
const coerceDate = z.coerce.date(); // Converts strings to Dates

const trimmedString = z.preprocess(
  val => typeof val === 'string' ? val.trim() : val,
  z.string()
);

const safeNumber = z.number().catch(0); // Returns 0 on parse failure

const describedSchema = z.object({
  name: z.string().describe("The user's full name"),
  age: z.number().describe("Age in years")
});

const exampleSchema = z.object({
  email: z.string().email().example("user@example.com")
});