Qowaiv.js

Domain-driven design bottom up

Qowaiv is a (Single) Value Object library. It aims to model reusable (Single) Value Objects that can be used a wide variety of modeling scenarios, both inside and outside a Domain-driven context.

Supported scenarios include parsing, formatting, validation, (de)serialization, and domain specific logic.

TypeScript

As developement tool, we addopted TypeScript.

Single Value Object

A Value Object that can be represented by a single scalar.

Qowaiv types

Guid

information in computer systems.

let empty = Guid.Empty();  // 00000000-0000-0000-0000-000000000000
let next = Guid.newGuid(); // 123E4567-E89B-12D3-A456-426655440000
let str = next.format("B"); // {123E4567-E89B-12D3-A456-426655440000}

Qowaiv Interfaces

IFormattable

As JavaScript does not support method overloading, this interface makes explicit by including toString() and format(f: string) that the format method should be the overloaded version of toString.

interface IFormattable
{
    toString(): string;
    format(f: string): string;
}

IEquatable

As JavaScript does not have a way to support equals overloading as a lot of other languages do, but it gives something.

interface IEquatable
{
    equals(other: any): boolean;
}

Compared with the follow snippet, you could work arround it, although using a function eq(l, r) over l === r is obvious not trivial, or close to ideal.

function eq(l, r) {
    if (arguments.length !== 2) { throw new Error('Invalid number of arguments.'); }
    if (l !== null && l !== undefined && typeof (l.equals) === 'function') {
        return l.equals(r);
    }
    if (r !== null && r !== undefined && typeof (r.equals) === 'function') {
        return r.equals(l);
    }
    return l === r;
} 

IJsonStringifyable

To support JSON.stringify() this interface was introduced.

interface IJsonStringifyable {
    toJSON(): any;
}