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docs(transformer): add to arrow functions transform docs (#5989)

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Add details of `spec` option and shorten example.
This commit is contained in:
overlookmotel 2024-09-23 09:49:39 +00:00
parent 7b90d794d1
commit 860f108a75
1 changed files with 60 additions and 11 deletions
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71
crates/oxc_transformer/src/es2015/arrow_functions.rs
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@ -8,6 +8,7 @@
//!
//! Implementation is incomplete at present. Still TODO:
//!
//! * `spec` option.
//! * Handle `arguments` in arrow functions.
//! * Handle `new.target` in arrow functions.
//! * Handle arrow function in function params (`function f(g = () => this) {}`).
@ -28,10 +29,10 @@
//! console.log(double); // [2,4,6]
//!
//! var bob = {
//! _name: "Bob",
//! _friends: ["Sally", "Tom"],
//! name: "Bob",
//! friends: ["Sally", "Tom"],
//! printFriends() {
//! this._friends.forEach(f => console.log(this._name + " knows " + f));
//! this.friends.forEach(f => console.log(this.name + " knows " + f));
//! },
//! };
//! console.log(bob.printFriends());
@ -40,9 +41,7 @@
//! Output:
//! ```js
//! var a = function() {};
//! var a = function(b) {
//! return b;
//! };
//! var a = function(b) { return b; };
//!
//! const double = [1, 2, 3].map(function(num) {
//! return num * 2;
@ -50,19 +49,69 @@
//! console.log(double); // [2,4,6]
//!
//! var bob = {
//! _name: "Bob",
//! _friends: ["Sally", "Tom"],
//! name: "Bob",
//! friends: ["Sally", "Tom"],
//! printFriends() {
//! var _this = this;
//!
//! this._friends.forEach(function(f) {
//! return console.log(_this._name + " knows " + f);
//! this.friends.forEach(function(f) {
//! return console.log(_this.name + " knows " + f);
//! });
//! },
//! };
//! console.log(bob.printFriends());
//! ```
//!
//! ## Options
//!
//! ### `spec`
//!
//! `boolean`, defaults to `false`.
//!
//! This option enables the following:
//! * Wrap the generated function in .bind(this) and keeps uses of this inside the function as-is,
//! instead of using a renamed this.
//! * Add a runtime check to ensure the functions are not instantiated.
//! * Add names to arrow functions.
//!
//! #### Example
//!
//! Using spec mode with the above example produces:
//!
//! ```js
//! var _this = this;
//!
//! var a = function a() {
//! babelHelpers.newArrowCheck(this, _this);
//! }.bind(this);
//! var a = function a(b) {
//! babelHelpers.newArrowCheck(this, _this);
//! return b;
//! }.bind(this);
//!
//! const double = [1, 2, 3].map(
//! function(num) {
//! babelHelpers.newArrowCheck(this, _this);
//! return num * 2;
//! }.bind(this)
//! );
//! console.log(double); // [2,4,6]
//!
//! var bob = {
//! name: "Bob",
//! friends: ["Sally", "Tom"],
//! printFriends() {
//! var _this2 = this;
//! this.friends.forEach(
//! function(f) {
//! babelHelpers.newArrowCheck(this, _this2);
//! return console.log(this.name + " knows " + f);
//! }.bind(this)
//! );
//! },
//! };
//! console.log(bob.printFriends());
//! ```
//!
//! ## Implementation
//!
//! Implementation based on [@babel/plugin-transform-arrow-functions](https://babel.dev/docs/babel-plugin-transform-arrow-functions).