# will-did-set-decorator

> Class property decorator to handle will-set and did-set

Latest version **0.0.4** (published 2021-10-17) · MIT license · 0 weekly downloads

## Install

```sh
npm install will-did-set-decorator
pnpm add will-did-set-decorator
yarn add will-did-set-decorator
bun add will-did-set-decorator
```

## Health

**Score 15/100 (F)** — status: abandoned.

Positive: no vulnerabilities.

Warnings: low downloads; no types; no esm support; pre 1.0.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 0.0.4 |
| Published | 2021-10-17 |
| First published | 2021-10-13 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | none |
| Module format | CommonJS |
| Dependencies | 0 |
| Unpacked size | 13.4 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 0 |
| Author | Filipe Roberto Beck |
| Maintainers | filipe.beck |

## Links

- npm: https://www.npmjs.com/package/will-did-set-decorator
- Repository: https://github.com/FilipeBeck/will-did-set-decorator
- npm.io page: https://npm.io/package/will-did-set-decorator

## Recent versions

- 0.0.4 (latest) — 2021-10-17
- 0.0.3 — 2021-10-15
- 0.0.2 — 2021-10-14
- 0.0.1 — 2021-10-13

## README

# Decorator for `willSet` and `didSet`

Class decorators to listen to member assignments before and after they occur.

## Instalação

NPM: https://www.npmjs.com/package/will-did-set-decorator

## willSet

```typescript
function willSet(handler: (newValue: any) => void): PropertyDecorator
```

Attach a handler that will be executed just before the property is modified. The order of calls is from subclass to superclass. That is, if the class `A` has a `foo` property decorated with `willSet` and the subclass `B` decorates the same property with `willSet`, first `B.willSet` will be called, after `A.willSet`.

- `handler`: Function called with the new value (the value after assignment).

### Example:

```typescript
class SuperClass {
  @willSet(function(this: SuperClass, newValue: string) {
    console.log('SuperClass', this.prop, newValue)
  })
  public prop?: number
}

class SubClass extends SuperClass {
  @willSet(function(this: SubClass, newValue: string) {
    console.log('SubClass', this.prop, newValue)
  })
  public override prop?: number
}

const clazz = new SubClass()
// Calls `SubClass.willSet()`, then `SuperClass.willSet()`
clazz.prop = 42
/*
 * Log order:
 * 1 - 'SubClass', undefined, 42
 * 2 - 'SuperClass', undefined, 42
 */
```

## didSet

```typescript
function didSet(handler: (oldValue: any) => void): PropertyDecorator
```

Attach a handler that will be executed just after the property is modified. The order of calls is from superclass to subclass. That is, if the class `A` has a `foo` property decorated with `didSet` and the subclass `B` decorates the same property with `didSet`, first `A.didSet` will be called, after `B.didSet`.
- `handler`: handler Function called with the old value (the value before assignment - undefined in the first call).

### Example:

```typescript
class SuperClass {
  @didSet(function(this: SuperClass, oldValue: string) {
    console.log('SuperClass', this.prop, oldValue)
  })
  public prop?: number
}

class SubClass extends SuperClass {
  @didSet(function(this: SubClass, oldValue: string) {
    console.log('SubClass', this.prop, oldValue)
  })
  public override prop?: number
}

const clazz = new SubClass()
// Calls `SuperClass.didSet()`, then `SubClass.didSet()`
clazz.prop = 42
/*
 * Log order:
 * 1 - 'SuperClass', 42, undefined
 * 2 - 'SubClass', 42, undefined
 */
```

---
_Source: https://npm.io/package/will-did-set-decorator · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._