Catch Decorator

!npm
!npm bundle size
!NPM

ECMAScript/TypeScript Catch decorator for classes and functions. Based on @enkot/catch-decorator.

Install

``
npm install @magna_shogun/catch-decorator

yarn add @magna_shogun/catch-decorator
`

Usage


> catch-decorator works with any ECMAScript/TypeScript class. If you use Babel, babel-plugin-transform-decorators-legacy is needed. If you use TypeScript, enable --experimentalDecorators flag.

#### Catch
Decorate a function to catch the specific type of error.
`
class Messenger {
@Catch(ReferenceError, (err, ctx) => {...})
getMessages() {
throw new ReferenceError('ReferenceError here!');
...
}
}
`

You can stack decorators to catch and handle different types of error.
`
class Messenger {
@Catch(TypeError, (err, ctx) => {...})
@Catch(ReferenceError, (err, ctx) => {...})
getMessages() {
if (conditionA) {
throw new ReferenceError('ReferenceError here!');
...
}
if (conditionB) {
throw new TypeError('TypeError here!');
...
}
}
}
`

It also works for async functions.
`
class Messenger {
@Catch(ServerError, (err, ctx) => {...})
async getMessages() {
return fetch(myRequest).then(response => { // can throw ServerError
...
});
}
}
`

#### CatchAll
You can catch any type of errors using the CatchAll decorator.
`
class Messenger {
@CatchAll((err, ctx) => {...})
getMessages() {
// Both ReferenceError and TypeError will be catched
if (conditionA) {
throw new ReferenceError('ReferenceError here!');
...
}
if (conditionB) {
throw new TypeError('TypeError here!');
...
}
}
}
`

#### Class Decoration
If you want to apply the same decorator to all the functions of a class (excluding its constructor), you can add the decorator to the class.
`
class Messenger {
@Catch(ReferenceError, (err, ctx) => {...})
getMessages() {
throw new ReferenceError('ReferenceError here!');
...
}

@Catch(ReferenceError, (err, ctx) => {...})
getPosts() {
throw new ReferenceError('ReferenceError here!');
...
}
}
`

This can be re-written as follows.
`
@Catch(ReferenceError, (err, ctx) => {...})
class Messenger {
getMessages() {
throw new ReferenceError('ReferenceError here!');
...
}

getPosts() {
throw new ReferenceError('ReferenceError here!');
...
}
}
`

#### HandlerFunction
The callback for the Catch and CatchAll decorators is of type HandlerFunction.
`
type HandlerFunction = (error: Error, ctx: any) => void;
`

error is the caught error or exception.
ctx is the context (this`) of the function were the error was thrown.

License

MIT