enzo418 / typed-promise

@enzo418/typed-promise Library

This library provides a TypeScript implementation of Promises, with additional features such as cancellation and typed responses. It also includes an HTTP client that returns these typed promises.

Installation

To install the library, use npm:

npm install @enzo418/typed-promise

Usage

TypedPromise

Import the TypedPromise class from the library:

import { TypedPromise } from '@enzo418/typed-promise';

You can then create a new TypedPromise and use it like a standard Promise, with additional type safety:

import { TypedPromise } from "@enzo418/typed-promise";

let promise = new TypedPromise<number, MyError>((resolve, reject) => {
    if (Math.random() > 0.5) {
        resolve(42);
    } else {
        reject(new MyError({ message: 'Something went wrong', code: 42 }));
    }
});

HttpClient and ProcessPromise

The library also includes an HTTP client that returns Promises but, if you know the backend's error types, you can convert them to TypedPromises using the process method:

import { TypedPromise, HttpClient, IProblemJson, processPromise } from "@enzo418/typed-promise";

interface ResponseDTO {
    name: string;
    age: number;
}

interface ResponseError extends IProblemJson {
    traceId: string;
}

const client = new HttpClient('myapiurl.com');

const parameters = {
    include: 'name,age',
};

const init: RequestInit = {
    headers: { // Example authorization header
        'Authorization': 'Bearer ' + 'mytoken',
    },
};

processPromise<ResponseDTO, ResponseError>(
    client.get('/users/1', parameters, init),
).ok((dto: ResponseDTO) => {
    // Success! status is in the range of 200 - 299.
    // handle success with dto
}).fail((error: ResponseError) => {
    // Error. status is not in the range of 200 - 299 or there was a network error.
    // handle error with error.traceId
});