resguard is a tiny utility that wraps promises and returns an object or tuple with data and error properties. It's useful for handling errors in async functions without having to use try/catch blocks.

highlights

- 🛡 Wraps promises and returns an object or tuple with data and error properties
- 🎯 TypeScript support with type checking
- 🛠️ Custom error handling support
- ⚡ Minimal dependencies and small bundle size

usage

``bash
npm install resguard
`

`typescript
import { resguard } from 'resguard'

async function fetchData() {
const client = new APIClient()

const { data, error } = await resguard(client.getItems())
if (error)
handle(error)

const updated = await resguard(client.updateItems(data))
if (updated.error)
handle(updated.error)

return updated.data
}
`
Both the data and error properties of the result are correctly typed


`typescript
import { resguard } from 'resguard'

const result = resguard(() => {
if (Math.random() > 0.5)
return true
else
throw new Error('Something went wrong')
})

if (result.error)
handle(result.error)
`
resguard can also be used with functions. When they are sync, the result also is!

`typescript
import { resguard } from 'resguard'

const result = await resguard(async () => {
const client = new APIClient()
const items = await client.getItems()
return items.map(item => item.id)
})

if (result.error)
handle(result.error)
`
resguard can also be used with async functions.

`typescript
import { resguardFn } from 'resguard'

const safeJSONParse = resguardFn(JSON.parse)

let result = safeJSONParse('{ "test": 1 }')
console.log(result.data) // { test: 1 }

result = safeJSONParse('{ missing the other one')
console.log(result.error) // SyntaxError: Unexpected character 'm' (1:2)
`
resguardFn is a wrapper around resguard that takes a function as an argument and returns a function that can be called with the same arguments, but guarded.


using tuples

resguard can also return a tuple with data and error values:

`javascript
import { resguard } from 'resguard';

async function fetchData() {
const service = new DataService();
const [[data, error]] = await resguard(service.getItems());

if (error) {
console.error("Error:", error);
return;
}

return data;
}
`

custom error handling

resguard supports custom error handling by allowing you to override the error type:

`javascript
import { resguard } from 'resguard';

class CustomError extends Error {}

async function fetchData() {
const service = new DataService();
const [[data, error]] = await resguard(() => throw new CustomError('damn!'), CustomError);

if (error) {
console.error("Custom Error:", error);
console.log(error instanceof CustomError) // true
return;
}

return data;
}
``

[npm-version-src]: https://img.shields.io/npm/v/resguard?style=flat&colorA=18181B&colorB=F0DB4F
[npm-version-href]: https://npmjs.com/package/resguard
[npm-downloads-src]: https://img.shields.io/npm/dm/resguard?style=flat&colorA=18181B&colorB=F0DB4F
[npm-downloads-href]: https://npmjs.com/package/resguard
[codecov-src]: https://img.shields.io/codecov/c/gh/henrycunh/resguard/main?style=flat&colorA=18181B&colorB=F0DB4F
[codecov-href]: https://codecov.io/gh/henrycunh/resguard