Package Exports

@vladbasin/ts-result
@vladbasin/ts-result/dist/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (@vladbasin/ts-result) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

ts-result

This library brings elements of functional programming to TypeScript/JavaScript. See Use cases section for details

Install

npm

npm install @vladbasin/ts-result

yarn

yarn add @vladbasin/ts-result

Use cases

Asynchronous code chaining

Let's assume you have to work with the set of async methods, which load data from backend and return Promise. Normally you use try\catch, async\await, then\catch, if\then\else to handle results. Readability isn't really good with this approach.

showLoader();
try {
    const wallet = await getWalletAsync();
    if (wallet.money < 10) {
        alert("Not enough money");
        return;
    }
    const item = await getItemAsync();
    const response = await purchaseAsync(item);
    if (!response.success) {
        alert(response.error);
        return;
    }
    log("Purchase success");
}
catch (error) {
    alert(error);
}
finally {
    hideLoader();
}

However, with this library instead you can write nice readable chains of methods:

import { Result } from "@vladbasin/Result";

showLoader();
Result
    .FromPromise(getWalletAsync())
    .ensure(wallet => wallet.money > 10, "Not enough money")
    .onSuccess(() => getItemAsync(itemId))
    .onSuccess(item => purchaseAsync(item))
    .ensure(response => response.success, response.error)
    .onFailure(error => alert(error))
    .onSuccess(() => log("Purchase success"))
    .onBoth(result => hideLoader())
    .run();

Rid of primitive obsession

Without this library (poor readability, code repeats)

const usernameValidation = validateUsername(username);
if (!usernameValidation.success) {
    alert(usernameValidation.error)
    return;
}
const passwordValidation = validatePassword(password);
if (!passwordValidation.success) {
    alert(passwordValidation.error)
    return;
}
const passwordRepeatValidation = validatePasswordRepeat(passwordRepeat, password);
if (!passwordRepeatValidation.success) {
    alert(passwordRepeatValidation.error)
    return;
}

With this library (readable code, reusable logic)

import { Result } from "@vladbasin/Result";

Result
    .Ok(username)
    .onSuccess(() => validateUsername(username))
    .onSuccess(() => validatePassword(password))
    .onSuccess(() => validatePasswordRepeat(passwordRepeat, password))
    .onFailure(error => alert(error))
    .run();

See inline comments for more documentation