hype-type v0.3.1

hype-type

Install

npm i hype-type

Usage

Using hype-type you can check the type of value using built-in library types or your own ones

'use strict'

const { Type } = require('hype-type');

Type.Date.is(new Date()); // true

const integer = new Type(value => 
  Type.Number.is(value) &&
  value % 1 === 0
);

integer.is(123); // true
integer.is(12.3); // false

API

Library exports Type class with assigned built-in types.

Type class

Type instances are created by defining type's its constraint, extending an existing type or wrapping a class:

/**
 * Simple number type
 */
const number = new Type(value => typeof value === 'number');
number.is(10); // true
number.is('10'); // false

/**
 * Extending an existing type
 */
const integer = Type.extend(number, value => value % 1 === 0);
integer.is(10); // true
integer.is(10.1); // false

/**
 * Create a type from a class
 */
const map = Type.from(Map);
map.is(new Map()); // true
map.is({}); // false

Type methods:

• is(value) - check whether the value accepts type's constraint

Type static methods:

• extend(type, constraint) - create a new type, inheriting all parent's constraints
• from(class) - create a new type, which values are instances of class
• union(...types) - create a TypeUnion instance from given types

TypeUnion class

TypeUnion extends Type class, so it also has an is method.

TypeUnion methods:

• of(value) - return the type of value, if value accepts some from TypeUnion types.

const unionType = Type.union(Type.Number, Type.String);
unionType.is(123); // true
unionType.is('123'); // true
unionType.is({}); // false

unionType.of(123); // Type.Number
unionType.of('123'); // Type.String
unionType.of({}); // undefined

Schema class

Schema class is useful for defining object property types

const { Type, Schema } = require('hype-type');

const person = new Schema({
  id: Type.Number,
  name: Type.Stirng,
  born: Type.Date,
});

person.is({
  id: 1,
  name: 'Alexander',
  born: new Date(),
}); // true

Schema extends Type class, so it has the same methods.

You can also define optional properties using [] syntax:

const person = new Schema({
  id: Type.Number,
  name: Type.String,
  born: [Type.Date], // optional
});

person.is({
  id: 1,
  name: 'Alexander',
}); // true

person.is({
  name: 'Alexander',
}); // false, required property `id` is missing