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https://github.com/webcarrot/proto-polyfill
Provide __proto__ with some limitations
https://github.com/webcarrot/proto-polyfill
babel class es6 ie10 ie9 polyfill proto static webpack
Last synced: about 1 month ago
JSON representation
Provide __proto__ with some limitations
- Host: GitHub
- URL: https://github.com/webcarrot/proto-polyfill
- Owner: webcarrot
- License: mit
- Archived: true
- Created: 2017-07-13T14:26:55.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2018-08-30T12:59:57.000Z (about 6 years ago)
- Last Synced: 2024-09-24T08:02:13.978Z (about 1 month ago)
- Topics: babel, class, es6, ie10, ie9, polyfill, proto, static, webpack
- Language: JavaScript
- Homepage:
- Size: 20.5 KB
- Stars: 10
- Watchers: 3
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# proto-polyfill · [](https://github.com/webcarrot/proto-polyfill/blob/master/LICENSE) [](https://www.npmjs.com/package/proto-polyfill)
Provide `__proto__` with some limitations
## browsers that need this polyfill
In general old browsers that **not** provide legacy `__proto__` and **support** `Object.defineProperty`, `Object.getPrototypeOf`, `Object.getOwnPropertyNames`, `Object.getOwnPropertyDescriptor` and `Object.create`:
- IE 9
- IE 10
IE 8 is **not** supported.
### why and when
If you do things like:
./tests/class-like.js
or (ES6 version):
```js
class X {
static get foo() {
return "xFoo";
}
get foo() {
return this.constructor.foo + " by instance!";
}
}
X.s = { s: "x" };
X.f = "X";
class Y extends X {
static get foo() {
return this.__proto__.foo + " > yFoo";
}
}
Y.s = {
s: "y"
};
Y.f = "Y";
class Z extends Y {
static get foo() {
return this.__proto__.foo + " > zFoo";
}
get foo() {
return "My special Z foo " + super.foo;
}
}
Z.f = "Z";
var x = new X();
var y = new Y();
var z = new Z();
console.log(x.foo); // xFoo by instance!
console.log(y.foo); // xFoo > yFoo by instance!
console.log(z.foo); // My special Z foo xFoo > yFoo > zFoo by instance!
console.log(x.constructor.s.s); // x
console.log(x.constructor.f); // X
console.log(y.constructor.s.s); // y
console.log(y.constructor.f); // Y
console.log(z.constructor.s.s); // y
console.log(z.constructor.f); // Z
```
...and code produced by compliler ( babel 6.x ) not work properly in old browsers like ie9-10.
## installation
`npm install --save-dev proto-polyfill`
And use like polyfill...
## limitations
Look at ./tests/limitations.js
```js
var x = {
a: "xa"
};
function X() {}
X.prototype.a = "Xa";
X.prototype.cv = "XCV";
X.prototype.ab = function() {
return "ab:" + this.a;
};
Object.defineProperty(X.prototype, "c", {
get: function() {
return this.ab() + ":" + this.cv;
}
});
// no way to replace object prototype "in place" ?
x.__proto__ = X.prototype;
console.log(x instanceof X); // invalid log: false should true
// but some kind emulation works
console.log(x.a); // ok log: "xa";
console.log(x.ab()); // ok log: "ab:xa";
console.log(x.c); // ok log: "ab:xa:XCV";
// normal instance
var iX = new X();
console.log(iX instanceof X); // ok log: true
console.log(iX.a); // ok log: "Xa";
console.log(iX.ab()); // ok log: "ab:Xa";
console.log(iX.c); // ok log: "ab:Xa:XCV";
// override
X.prototype.cv = "XCV2";
console.log(x.c); // ok log: "ab:xa:XCV2";
x.cv = "XCV3";
console.log(x.c); // ok log: "ab:xa:XCV3";
// but
X.prototype.newProp = "newProp";
console.log(x.newProp); // invalid log: undefined should "newProp";
```
### Pseudo Symbol()
Pseudo `Symbol()` props are skipped (core-js Set polyfill use it)
### Object.setPrototypeOf
Only emultation
### Object.getPrototypeOf
Override to make super() work in Babel 7
## tests
`./tests/index.html`
PR welcome.