https://github.com/aleclarson/spy-on

https://github.com/aleclarson/spy-on

Last synced: 19 days ago
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• Host: GitHub
• URL: https://github.com/aleclarson/spy-on
• Owner: aleclarson
• Created: 2020-11-19T21:47:56.000Z (almost 4 years ago)
• Default Branch: master
• Last Pushed: 2020-11-19T22:43:22.000Z (almost 4 years ago)
• Last Synced: 2024-10-13T04:06:24.928Z (24 days ago)
• Language: TypeScript
• Homepage:
• Size: 42 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# @alloc/spy-on

Observe assignments to any writable, configurable object property.

```js

import spyOn from '@alloc/spy-on'

const obj = { a: 0 }

// The same property can be spied on multiple times.

const logger = spyOn(obj, 'a', console.log)

const mirror = spyOn(obj, 'a', a => (obj.b = a))

obj.a++        // logs "1"

obj.a == obj.b // => true

// Spies can be disposed.

logger.dispose()

obj.a++        // logs nothing

obj.a == obj.b // => true

mirror.dispose()

obj.a++        // logs nothing

obj.a == obj.b // => false

// Once all spies are disposed, the original descriptor 

// is restored.

Object.defineProperty(obj, 'a').value == 3 // => true

```