Add missing docs for proposal-private-methods (#1967)

Fixes #1966.

docs/plugin-proposal-private-methods.md

@@ -0,0 +1,141 @@
+---
+id: babel-plugin-proposal-private-methods
+title: @babel/plugin-proposal-private-methods
+sidebar_label: proposal-private-methods
+---
+
+## Example
+
+```js
+class Counter extends HTMLElement {
+  #xValue = 0;
+
+  get #x() { return this.#xValue; }
+  set #x(value) {
+    this.#xValue = value;
+    window.requestAnimationFrame(
+      this.#render.bind(this));
+  }
+
+  #clicked() {
+    this.#x++;
+  }
+}
+```
+
+## Installation
+
+```sh
+$ npm install @babel/plugin-proposal-private-methods
+```
+
+## Usage
+
+### Via `.babelrc` (Recommended)
+
+**.babelrc**
+
+Without options:
+
+```json
+{
+  "plugins": ["@babel/plugin-proposal-private-methods"]
+}
+```
+
+With options:
+
+```json
+{
+  "plugins": [["@babel/plugin-proposal-private-methods", { "loose": true }]]
+}
+```
+
+### Via CLI
+
+```sh
+$ babel --plugins @babel/plugin-proposal-private-methods script.js
+```
+
+### Via Node API
+
+```javascript
+require("@babel/core").transform("code", {
+  plugins: ["@babel/plugin-proposal-private-methods"],
+});
+```
+
+## Options
+
+### `loose`
+
+`boolean`, defaults to `false`.
+
+> Note: The `loose` mode configuration setting _must_ be the same as [`@babel/proposal-class-properties`](plugin-proposal-class-properties.md).
+
+When true, private methods will be assigned directly on its parent
+via `Object.defineProperty` rather than a `WeakSet`. This results in improved
+performance and debugging (normal property access vs `.get()`) at the expense
+of potentially leaking "privates" via things like `Object.getOwnPropertyNames`.
+
+Let's use the following as an example:
+
+```javascript
+class Foo {
+  constructor() {
+    this.publicField = this.#privateMethod();
+  }
+
+  #privateMethod() {
+    return 42;
+  }
+}
+```
+
+By default, this becomes:
+
+```javascript
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+
+  _privateMethod.add(this);
+
+  this.publicField = babelHelpers
+    .classPrivateMethodGet(this, _privateMethod, _privateMethod2)
+    .call(this);
+};
+
+var _privateMethod = new WeakSet();
+
+var _privateMethod2 = function _privateMethod2() {
+  return 42;
+};
+```
+
+With `{ loose: true }`, it becomes:
+
+```javascript
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+  Object.defineProperty(this, _privateMethod, {
+    value: _privateMethod2,
+  });
+  this.publicField = babelHelpers
+    .classPrivateFieldLooseBase(this, _privateMethod)
+    [_privateMethod]();
+};
+
+var _privateMethod = babelHelpers.classPrivateFieldLooseKey("privateMethod");
+
+var _privateMethod2 = function _privateMethod2() {
+  return 42;
+};
+```
+
+## References
+
+- [Proposal: Private methods and getter/setters for JavaScript classes](https://github.com/tc39/proposal-private-methods)

docs/plugins.md

@@ -90,6 +90,7 @@ These plugins apply transformations to your code.
 - [numeric-separator](plugin-proposal-numeric-separator.md)
 - [optional-chaining](plugin-proposal-optional-chaining.md)
 - [pipeline-operator](plugin-proposal-pipeline-operator.md)
+- [private-methods](plugin-proposal-private-methods.md)
 - [throw-expressions](plugin-proposal-throw-expressions.md)
 
 ### Minification

website/versioned_docs/version-7.2.0/plugin-proposal-private-methods.md

@@ -0,0 +1,137 @@
+---
+id: version-7.2.0-babel-plugin-proposal-private-methods
+title: @babel/plugin-proposal-private-methods
+sidebar_label: proposal-private-methods
+original_id: babel-plugin-proposal-private-methods
+---
+
+> Note: Support for private accessors (getters and setters) was added in [7.3.0](https://babeljs.io/blog/2019/01/21/7.3.0)!
+
+## Example
+
+```js
+class Counter extends HTMLElement {
+  #xValue = 0;
+
+  #clicked() {
+    this.#x++;
+  }
+}
+```
+
+## Installation
+
+```sh
+$ npm install @babel/plugin-proposal-private-methods
+```
+
+## Usage
+
+### Via `.babelrc` (Recommended)
+
+**.babelrc**
+
+Without options:
+
+```json
+{
+  "plugins": ["@babel/plugin-proposal-private-methods"]
+}
+```
+
+With options:
+
+```json
+{
+  "plugins": [["@babel/plugin-proposal-private-methods", { "loose": true }]]
+}
+```
+
+### Via CLI
+
+```sh
+$ babel --plugins @babel/plugin-proposal-private-methods script.js
+```
+
+### Via Node API
+
+```javascript
+require("@babel/core").transform("code", {
+  plugins: ["@babel/plugin-proposal-private-methods"],
+});
+```
+
+## Options
+
+### `loose`
+
+`boolean`, defaults to `false`.
+
+> Note: The `loose` mode configuration setting _must_ be the same as [`@babel/proposal-class-properties`](plugin-proposal-class-properties.md).
+
+When true, private methods will be assigned directly on its parent
+via `Object.defineProperty` rather than a `WeakSet`. This results in improved
+performance and debugging (normal property access vs `.get()`) at the expense
+of potentially leaking "privates" via things like `Object.getOwnPropertyNames`.
+
+Let's use the following as an example:
+
+```javascript
+class Foo {
+  constructor() {
+    this.publicField = this.#privateMethod();
+  }
+
+  #privateMethod() {
+    return 42;
+  }
+}
+```
+
+By default, this becomes:
+
+```javascript
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+
+  _privateMethod.add(this);
+
+  this.publicField = babelHelpers
+    .classPrivateMethodGet(this, _privateMethod, _privateMethod2)
+    .call(this);
+};
+
+var _privateMethod = new WeakSet();
+
+var _privateMethod2 = function _privateMethod2() {
+  return 42;
+};
+```
+
+With `{ loose: true }`, it becomes:
+
+```javascript
+var Foo = function Foo() {
+  "use strict";
+
+  babelHelpers.classCallCheck(this, Foo);
+  Object.defineProperty(this, _privateMethod, {
+    value: _privateMethod2,
+  });
+  this.publicField = babelHelpers
+    .classPrivateFieldLooseBase(this, _privateMethod)
+    [_privateMethod]();
+};
+
+var _privateMethod = babelHelpers.classPrivateFieldLooseKey("privateMethod");
+
+var _privateMethod2 = function _privateMethod2() {
+  return 42;
+};
+```
+
+## References
+
+- [Proposal: Private methods and getter/setters for JavaScript classes](https://github.com/tc39/proposal-private-methods)