Basic Types

Simple type declarations


// String
new SchemaBuilder().string().build();
// { type: "string" }
 
// Number
new SchemaBuilder().number().build();
// { type: "number" }
 
// Integer
new SchemaBuilder().integer().build();
// { type: "integer" }
 
// Boolean
new SchemaBuilder().boolean().build();
// { type: "boolean" }
 
// Null
new SchemaBuilder().null().build();
// { type: "null" }

Multiple types

Chain type methods to create a type array.


const flexibleSchema = new SchemaBuilder().string().number().build();
// { type: ["string", "number"] }
 
const nullableString = new SchemaBuilder().string().null().minLength(5).build();
// { type: ["string", "null"], minLength: 5 }

The first type you call determines which keywords TypeScript exposes. This matters when adding constraints — see TypeScript Type Locking.

Universal keywords

These work with any type and are not locked to a specific type builder:


const schema = new SchemaBuilder()
  .$schema("https://json-schema.org/draft/2020-12/schema")
  .$id("https://json-schema.org/draft/2020-12/schema")
  .title("User Email")
  .description("The user's primary email address")
  .default("user@example.com")
  .examples("alice@example.com", "bob@example.com")
  .enum(["alice@example.com", "bob@example.com", "admin@example.com"])
  .readOnly()
  .build();

Keyword	Description
`.$schema(schema)`	Schema draft
`.$id(schemaId)`	Unique schema identifier
`.$ref(ref)`	Schema reference
`.$dynamicRef(dynamicRef)`	Dynamic schema reference
`.$anchor(anchor)`	Schema identifier
`.$dynamicAnchor(dynamicAnchor)`	Dynamic schema identifier
`.definitions(definitions)`	Schema definitions (Draft 7 and below)
`.$defs(defs)`	Schema definitions
`.title(title)`	Human-readable title
`.description(desc)`	Human-readable description
`.default(value)`	Default value
`.examples(...values)`	Example values
`.enum(values)`	Array of values (any type)
`.const(value)`	Single allowed value (any type)
`.readOnly()`	Mark as read-only
`.writeOnly()`	Mark as write-only
`.not(schema)`	Negation
`.anyOf(...schemas)`	Match at least one
`.allOf(...schemas)`	Match all
`.oneOf(...schemas)`	Match exactly one
`.if(condition)`	Conditional validation
`.errorMessage(msg)`	Custom error messages
`.option(key, value)`	Any custom keyword

These combine with any type:


// Enum with numbers
new SchemaBuilder().number().enum([1, 2, 3, 5, 8, 13]).build();
 
// Const with boolean
new SchemaBuilder().boolean().const(true).build();
 
// Composition without a type
new SchemaBuilder()
  .anyOf(
    (s) => s.string(),
    (s) => s.number(),
  )
  .build();