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Readme updates from babel.github.io [skip ci] (#4884)

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Henry Zhu
2016-11-22 14:17:17 -05:00
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parent 7e020272c1
commit 9d0518b715
5 changed files with 187 additions and 2 deletions
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17
packages/babel-plugin-syntax-async-functions/README.md
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@@ -1,6 +1,17 @@
# babel-plugin-syntax-async-functions
Allow parsing of async functions.
This plugin allows Babel to parse async functions.
## Example
**Syntax**
```javascript
(async function() {
await loadStory();
console.log("Yey, story successfully loaded!");
}());
```
## Installation
@@ -33,3 +44,7 @@ require("babel-core").transform("code", {
plugins: ["syntax-async-functions"]
});
```
## References
* [Proposal: Async Functions for ECMAScript](https://github.com/tc39/ecmascript-asyncawait)

22
packages/babel-plugin-syntax-async-generators/README.md
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@@ -2,6 +2,24 @@
Allow parsing of async generator functions.
## Example
**Syntax**
```javascript
async function* agf() {
await 1;
}
```
```js
async function f() {
for await (let x of y) {
g(x);
}
}
```
## Installation
```sh
@@ -33,3 +51,7 @@ require("babel-core").transform("code", {
plugins: ["syntax-async-generators"]
});
```
## References
* [Proposal: Asynchronous iteration for ECMAScript](https://github.com/tc39/proposal-async-iteration)

10
packages/babel-plugin-syntax-class-constructor-call/README.md
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@@ -1,6 +1,8 @@
# babel-plugin-syntax-class-constructor-call (deprecated)
Allow parsing of do expressions.
> Proposal Withdrawn: can be solved with decorators.
Allow parsing of call constructors.
## Installation
@@ -33,3 +35,9 @@ require("babel-core").transform("code", {
plugins: ["syntax-class-constructor-call"]
});
```
## References
* [Inactive Proposals](https://github.com/tc39/proposals/blob/master/inactive-proposals.md)
* [Proposal: Call Constructor](https://github.com/tc39/ecma262/blob/master/workingdocs/callconstructor.md)
* [Blog post: ECMAScript proposal: function-callable classes](http://www.2ality.com/2015/10/call-constructor-esprop.html)

72
packages/babel-plugin-transform-async-generator-functions/README.md
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@@ -2,6 +2,74 @@
Turn async generator functions and for-await statements to ES2015 generators
## Example
**In**
```javascript
async function* agf() {
await 1;
yield 2;
}
```
**Out**
```javascript
var _asyncGenerator = ...
let agf = (() => {
var _ref = _asyncGenerator.wrap(function* () {
yield _asyncGenerator.await(1);
yield 2;
});
return function agf() {
return _ref.apply(this, arguments);
};
})();
```
For await example
```js
async function f() {
for await (let x of y) {
g(x);
}
}
```
**Example Usage**
```js
async function* genAnswers() {
var stream = [ Promise.resolve(4), Promise.resolve(9), Promise.resolve(12) ];
var total = 0;
for await (let val of stream) {
total += await val;
yield total;
}
}
function forEach(ai, fn) {
return ai.next().then(function (r) {
if (!r.done) {
fn(r);
return forEach(ai, fn);
}
});
}
var output = 0;
forEach(genAnswers(), function(val) { output += val.value })
.then(function () {
console.log(output); // 42
});
```
[Try it Out in the REPL](https://babeljs.io/repl/#?babili=false&evaluate=true&lineWrap=false&presets=stage-3&code=async%20function*%20genAnswers()%20%7B%0A%20%20var%20stream%20%3D%20%5B%20Promise.resolve(4)%2C%20Promise.resolve(9)%2C%20Promise.resolve(12)%20%5D%3B%0A%20%20var%20total%20%3D%200%3B%0A%20%20for%20await%20(let%20val%20of%20stream)%20%7B%0A%20%20%20%20total%20%2B%3D%20await%20val%3B%0A%20%20%20%20yield%20total%3B%0A%20%20%7D%0A%7D%0A%0Afunction%20forEach(ai%2C%20fn)%20%7B%0A%20%20return%20ai.next().then(function%20(r)%20%7B%0A%20%20%20%20if%20(!r.done)%20%7B%0A%20%20%20%20%20%20fn(r)%3B%0A%20%20%20%20%20%20return%20forEach(ai%2C%20fn)%3B%0A%20%20%20%20%7D%0A%20%20%7D)%3B%0A%7D%0A%0Avar%20output%20%3D%200%3B%0AforEach(genAnswers()%2C%20function(val)%20%7B%20output%20%2B%3D%20val.value%20%7D)%0A.then(function%20()%20%7B%0A%20%20console.log(output)%3B%20%2F%2F%2042%0A%7D)%3B&experimental=true&loose=false&spec=false&playground=true&stage=0)
## Installation
```sh
@@ -33,3 +101,7 @@ require("babel-core").transform("code", {
plugins: ["transform-async-generator-functions"]
});
```
## References
* [Proposal: Asynchronous iteration for ECMAScript](https://github.com/tc39/proposal-async-iteration)

68
packages/babel-plugin-transform-class-constructor-call/README.md
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@@ -1,5 +1,67 @@
# babel-plugin-transform-class-constructor-call (deprecated)
> Proposal Withdrawn: can be solved with decorators.
This plugin allows Babel to transform class constructors.
It basically allows to use the [new.target](http://mdn.io/new.target) feature on ES2015 classes:
```js
class Point {
constructor(x, y) {
this.x = x;
this.y = y;
}
call constructor(x, y) {
return new Point(x, y);
}
}
let p1 = new Point(1, 2); // OK
let p2 = Point(3, 4); // OK
```
[Try in REPL](/repl/#?evaluate=true&presets=es2015%2Cstage-0&code=class%20Point%20%7B%0A%0A%20%20constructor(x%2C%20y)%20%7B%0A%20%20%20%20this.x%20%3D%20x%3B%0A%20%20%20%20this.y%20%3D%20y%3B%0A%20%20%7D%0A%0A%20%20call%20constructor(x%2C%20y)%20%7B%0A%20%20%20%20return%20new%20Point(x%2C%20y)%3B%0A%20%20%7D%0A%0A%7D%0A%0Alet%20p1%20%3D%20new%20Point(1%2C%202)%3B%20%2F%2F%20OK%0Alet%20p2%20%3D%20Point(3%2C%204)%3B%20%2F%2F%20OK)
## Example
### Date example
The javascript [Date](http://mdn.io/date) works this way:
```js
// You can get a Date instance using the new keyword
let now = new Date();
console.log(now.getMonth()); // Prints '3'
console.log(now.toString()); // Prints 'Mon Apr 11 2016 13:26:07 GMT+0100 (BST)'
// You can get a string of the current date using Date as a function:
let nowStr = Date();
console.log(nowStr); // Prints 'Mon Apr 11 2016 13:26:07 GMT+0100 (BST)'
```
It is currently possible to implement something like that using [new.target](http://mdn.io/new.target) (see [example in proposal](https://github.com/tc39/ecma262/blob/master/workingdocs/callconstructor.md#motivating-example)) and this new feature makes it available for ES2015 classes.
A date implementation could be:
```js
class Date {
constructor() {
// ...
}
call constructor() {
let date = new Date();
return date.toString();
}
}
let now = new Date(); // Get a Date instance
let nowStr = Date(); // Use the 'call constructor()' part to get a string value of the current date
```
[Try in REPL](/repl/#?evaluate=true&presets=es2015%2Cstage-0&code=class%20Date%20%7B%0A%20%20constructor()%20%7B%0A%20%20%20%20%2F%2F%20...%0A%20%20%7D%0A%0A%20%20call%20constructor()%20%7B%0A%20%20%20%20let%20date%20%3D%20new%20Date()%3B%0A%20%20%20%20return%20date.toString()%3B%0A%20%20%7D%0A%7D%0A%0Alet%20now%20%3D%20new%20Date()%3B%20%2F%2F%20Get%20a%20Date%20instance%0Alet%20nowStr%20%3D%20Date()%3B%20%2F%2F%20Use%20the%20'call%20constructor()'%20part%20to%20get%20a%20string%20value%20of%20the%20current%20date)
## Installation
```sh
@@ -31,3 +93,9 @@ require("babel-core").transform("code", {
plugins: ["transform-class-constructor-call"]
});
```
## References
* [Inactive Proposals](https://github.com/tc39/proposals/blob/master/inactive-proposals.md)
* [Proposal: Call Constructor](https://github.com/tc39/ecma262/blob/master/workingdocs/callconstructor.md)
* [Blog post: ECMAScript proposal: function-callable classes](http://www.2ality.com/2015/10/call-constructor-esprop.html)