Typed JSON

This library is a set of type definitions and utilities for dealing with JSON data in a type-safe way with TypeScript.

The most important type definitions are JSON.Value, JSON.Object, and JSON.Array, which correspond respectively to JSON values, objects, and arrays, as the names suggest.

The library also exports safely-typed versions of the standard JSON.parse() and JSON.stringify() functions.

Basic Usage

import * as JSON from 'ts-typed-json';

Types

interface JSON.Object

interface JSON.Object extends Record<string, JSON.Value> {}

interface JSON.Array

interface JSON.Array extends Array<JSON.Value> {}

type JSON.Value

type JSON.Value = null | boolean | number | string | JSON.Object | JSON.Array;

Type Testing API

function JSON.isNull(x: JSON.Value): x is null

Tests if a JSON value is null.

function JSON.isBoolean(x: JSON.Value): x is boolean

Tests if a JSON value is a boolean.

function JSON.isNumber(x: JSON.Value): x is number

Tests if a JSON value is a number.

function JSON.isString(x: JSON.Value): x is string

Tests if a JSON value is a string.

function JSON.isObject(x: JSON.Value): x is JSON.Object

Tests if a JSON value is a JSON object.

function JSON.isArray(x: JSON.Value): x is JSON.Array

Tests if a JSON value is a JSON array.

Type Cast API

function JSON.asNull(x: JSON.Value, prefix?: string): null

Casts a JSON value to null, throwing a TypeError if it fails.

The optional prefix argument allows callers to provide a contextual string describing the value that is being tested, for the sake of generating useful error messages in the case of a type error.

function JSON.asBoolean(x: JSON.Value, prefix?: string): boolean

Casts a JSON value to a boolean, throwing a TypeError if it fails.

The optional prefix argument allows callers to provide a contextual string describing the value that is being tested, for the sake of generating useful error messages in the case of a type error.

function JSON.asNumber(x: JSON.Value, prefix?: string): number

Casts a JSON value to a number, throwing a TypeError if it fails.

The optional prefix argument allows callers to provide a contextual string describing the value that is being tested, for the sake of generating useful error messages in the case of a type error.

function JSON.asString(x: JSON.Value, prefix?: string): string

Casts a JSON value to a string, throwing a TypeError if it fails.

The optional prefix argument allows callers to provide a contextual string describing the value that is being tested, for the sake of generating useful error messages in the case of a type error.

function JSON.asObject(x: JSON.Value, prefix?: string): JSON.Object

Casts a JSON value to a JSON object, throwing a TypeError if it fails.

The optional prefix argument allows callers to provide a contextual string describing the value that is being tested, for the sake of generating useful error messages in the case of a type error.

function JSON.asArray(x: JSON.Value, prefix?: string): JSON.Array

Casts a JSON value to a JSON array, throwing a TypeError if it fails.

The optional prefix argument allows callers to provide a contextual string describing the value that is being tested, for the sake of generating useful error messages in the case of a type error.

Serialization and Deserialization API

function parse(source: string): JSON.Value

Parses a source string as a JSON value.

function stringify(value: JSON.Value): string

Serializes a JSON value to a string.

function loadSync(path: string, encoding: BufferEncoding = 'utf8'): JSON.Value

Synchronously loads a JSON value from the filesystem.

function load(path: string, encoding: BufferEncoding = 'utf8'): Promise<JSON.Value>

Asynchronously loads a JSON value from the filesystem.