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https://github.com/azu/proxy-frozen-object
ES Proxy for `Object.freeze(object)`.
https://github.com/azu/proxy-frozen-object
freeze frozen proxy typescript
Last synced: 2 months ago
JSON representation
ES Proxy for `Object.freeze(object)`.
- Host: GitHub
- URL: https://github.com/azu/proxy-frozen-object
- Owner: azu
- License: mit
- Created: 2018-12-29T08:52:52.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2018-12-29T09:07:39.000Z (about 6 years ago)
- Last Synced: 2024-10-04T06:22:18.245Z (3 months ago)
- Topics: freeze, frozen, proxy, typescript
- Language: TypeScript
- Size: 12.7 KB
- Stars: 5
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# proxy-frozen-object [](https://travis-ci.org/azu/proxy-frozen-object)
ES Proxy for `Object.freeze(object)`.
Following proxy does not work correctly, `proxy-frozen-object` provide workaround.
```js
// DOES NOT WORK CORRECTLY
const proxied = new Proxy(Object.freeze(object), { ... });
```
## Why this library is needed?
[ES Proxy](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy) can not proxy frozen object **directly**.
Following example throw an `TypeError`.
> TypeError: proxy must report the same value for the non-writable, non-configurable property '"hello"'
```js
const myObject = {
hello: function() { return 'Hello!'; },
bye: function() { return 'Bye!'; }
};
console.log(myObject.hello()); // "Hello!"
console.log(myObject.bye()); // "Bye!"
// Freeze the object
Object.freeze(myObject);
// Create an proxy for myObject
const proxied = new Proxy(myObject, {
get: function(target, name, receiver) {
if (name === 'hello'){
return function() { return 'Hi!'; };
}
return Reflect.get(target, name, receiver);
}
});
// ERROR!
console.log(proxied.hello()); // TypeError: proxy must report the same value for the non-writable, non-configurable property '"hello"'
```
## How to resolve this issue?
This library that create an proxy for dummy object.
It is means that this library proxy `myObject` **indirectly**.
Following example proxy `myObject` indirectly for avoiding `TypeError`.
```js
const myObject = {
hello: function() { return 'Hello!'; },
bye: function() { return 'Bye!'; }
};
console.log(myObject.hello()); // "Hello!"
console.log(myObject.bye()); // "Bye!"
// Freeze the object
Object.freeze(myObject);
// Create an Proxy for {} (dummy object)
const proxied = new Proxy({}, {
get: function(target, name, receiver) {
if (name === 'hello'){
return function() { return 'Hi!'; };
}
// Reflect myObject instead of target
// if it is not `hello` method, return `myObject["hello"]`
return Reflect.get(myObject, name, receiver);
}
});
console.log(proxied.hello()); // "Hi!"
console.log(proxied.bye()); // "Bye!"
```
`proxy-frozen-object` do proxy the target indirectly.
## Install
Install with [npm](https://www.npmjs.com/):
npm install proxy-frozen-object
## Usage
### `createProxyForFrozenObject: (target: T, proxyHandler: ProxyHandler) => T`
`proxyHandler` is same API with [Methods of the handler object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy#Methods_of_the_handler_object) of ES Proxy.
```js
import { createProxyForFrozenObject } from "proxy-frozen-object";
const myObject = {
hello: function() {
return "Hello!";
},
bye: function() {
return "Bye!";
}
};
Object.freeze(myObject);
const proxied = createProxyForFrozenObject(myObject, {
get: function(target, name, receiver) {
if (name === "hello") {
return function() {
return "Hi!";
};
}
return Reflect.get(target, name, receiver);
}
});
console.log(proxied.hello()); // "Hi!"
```
## Changelog
See [Releases page](https://github.com/azu/proxy-frozen-object/releases).
## Running tests
Install devDependencies and Run `npm test`:
npm test
## Contributing
Pull requests and stars are always welcome.
For bugs and feature requests, [please create an issue](https://github.com/azu/proxy-frozen-object/issues).
1. Fork it!
2. Create your feature branch: `git checkout -b my-new-feature`
3. Commit your changes: `git commit -am 'Add some feature'`
4. Push to the branch: `git push origin my-new-feature`
5. Submit a pull request :D
## Author
- [github/azu](https://github.com/azu)
- [twitter/azu_re](https://twitter.com/azu_re)
## License
MIT © azu
## References
- [変更禁止のオブジェクトの一部のメソッドだけをES6 Proxyでオーバーライドする方法 - ククログ(2016-03-04)](https://www.clear-code.com/blog/2016/3/4.html)