await-handler-ts
v2.0.2
Published
Basic wrapper for await that allows handling of errors without try/catch blocks
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await-handler-ts
Simple signature to ease the paid of catching errors using async/await. This module will allow a simple method of catching errors from an await
handler without the need to wrap everything in try/catch blocks. This module is a Node.js only version based on await-to-js minus the typescript aspect. Credit for this module goes to Dima Grossman, as it was based off the code provided.
You continue to use async/await normally, except to wrap the function you are "awaiting", in this module to allow destructuring the returned array into variables. This is similar to the golang error handling syntax.
NOTE: This module works in Node 6+, but in order to use async/await, you need to use Node 8+ or compile with Babel.
THIS ADD SUPPORT FOR TYPESCRIPT OF THE AWAIT-HANDLER MADE BY KyleRoss
Install
Install via NPM:
npm i await-handler --save
Install via YARN:
yarn add await-handler
Usage
JS
const on = require('await-handler');
async function asyncFunctionExample() {
let [err, result] = await on(myAsyncTask());
if(err) {
throw err;
}
// ... handle the result
console.log(result);
}
ES import
import on from "await-handler";
TS
import on from "await-handler";
async function asyncFunctionExample() {
let [err, result] = await on(myAsyncTask());
if(err) {
throw err;
}
// ... handle the result
console.log(result);
}
// with errorProps
async function asyncFunctionExampleWithErrorProps() {
let [err, result] = await on<{props: string}, string>(myAsyncTask(), {props: "hey"});
if(err) {
console.log(err.props); // "hey"
throw err;
}
// ... handle the result
console.log(result);
}
// You can defined the type of the error adn the data by doing:
async function asyncFunctionExampleWithErrorPropsAndDataType() {
// the error will be of type Error or MyCustomError
// the data will be of type string
let [err, result] = await on<Error | MyCustomError, string>(myAsyncTask());
if(err) {
throw err; // err instanceof Error || err instanceof MyCustomError
}
// ... handle the result
console.log(result); // result instanceOf string
}
API
on(promise[, errorProps])
Type: Function
Adds handler to promise
in order to return an array which can be destructured. Optionally add additional properties to the returned error by providing an Object to errorProps
.
| Argument | Required? | Type | Description |
|------------|-----------|---------|------------------------------------------------------------|
| promise | Yes | Promise | Promise to wrap and return results for. |
| errorProps | No | Object | Optional object to append to the Error
if one is thrown. |
Generic
on<errorType, dataType>() {};
Examples:
async function basicExample() {
let [err, result] = await on(myAsyncTask());
if(err) throw err;
// ... handle the result
console.log(result);
}
async function errorPropsExample() {
let [err, result] = await on(myAsyncTask(), { customMessage: 'Something failed!' });
// With typescript
let [err, result] = await on<{customMessage: string}>(myAsyncTask(), { customMessage: 'Something failed!' })
if(err) {
console.error(err.customMessage);
return process.exit(1);
}
// ... handle the result
console.log(result);
}
Returns {Promise<Array>}
Returns Promise that resolves with array signature
[error, results]
. If an error is thrown,error
will be the the rejection from the promise andresults
will beundefined
. If an error is not thrown,error
will benull
andresults
will be the resolved value from the promise.
Tests
To run the tests:
npm install
npm run test
License
MIT License. See License in the repository.