Pcall.js

Errors as Values

zero-dependency

╶─ ╴╶ ╴╶ ╴╶ ╴╶ ╴╶ ─╴

• 🎌 Delegate Promise Resolutions
• 🧬 Lifecycle Callback Options
• 📍 Concise and Convenient Signature
• 📦 Zero-Dependency
• 🛑 Avoid try/catch ~~HELL~ 👹
• 🌟 Better Visibility and Control
• 🌐 Works in Node.js (ESM/CJS) and all modern browsers
• 〽️ Minimal Obsessive Disorder

basic

---

options

Inspiration

Lua approach to error handling is simple yet powerful. ^Lua:5.4 ^Lua:8.4, ^Lua:8.5

🔹 pcall.js is heavily inspired by Lua pcall with superpowers 🦄!

SYNOPSIS

pcall({f}, {arg1}, {...})

pcall() Calls function {f} with the given arguments in protected mode. This means that any error inside {f} is not propagated;

Instead, pcall catches the error and returns a tuple.

Its first element is the status code (a boolean), which is true if the call succeeds without errors. And all results from the call, on second element; [true, {res}]

In case of any error, pcall returns false plus the error message; [false, {err}]

Usage

# install
npm install pcall.js

// ESM
import Pcall from 'pcall.js'

// CJS
const Pcall = require('pcall.js')

Convert

// 🔻 BEFORE
try {
  const res = await readFile('./package.json', { encoding: 'utf8' })
} catch(error) {
  console.error(error, '🔥')
}

// ─────────────────
// 🔹AFTER
import Pcall from 'pcall.js'
const [err, user] = await Pcall(readFile, './package.json', { encoding: 'utf8' })

// 🔸THROW
err && throw new Error("XYZZY", { cause: err });

Options

import { readFile } from 'node:fs/promises'
import Pcall from 'pcall.js'

const path = './package.json'
const opts = { encoding: 'utf8' }

const pcall = new Pcall({
  onSuccess: (args, res) => { /*·🔹·*/ },
  onFailure: (args, err) => { /*·🔹·*/ },
  transformOnSuccess: (args, res) => { /*·🚧·*/ },
  transformOnFailure: (args, err) => { /*·🚧·*/ },
  cleanup: args => { /*·🔹·*/ },
  trace: true,
})

const [err, res] = await pcall(readFile, path, opts)

console.log('err', '::', err)
console.log('res', '::', res)

💡 Check [test/dev.test.js]

examples/ test/ for more examples

Development

# run test playground in watch mode
npm run dev

# build production
npm run build

# build stub
npm run build:stub

TODO

• 🌀 Lifecycle Hooks
• [.] 🔌 Serializer
• [.] 🧬 Parser
• [.] 📜 JSDoc
• [.] 🔧 ESLint
• [o] 📖 Docs
• [o] ⚠️ Tests
• [.] 💡 Examples

License

MIT