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@babel/plugin-transform-class-static-block

info

This plugin is included in @babel/preset-env, in ES2022

A class with a static block will be transformed into a static private property, whose initializer is the static block wrapped in an IIAFE (immediate invoked arrow function expression).

Example

JavaScript
class C {
static #x = 42;
static y;
static {
try {
this.y = doSomethingWith(this.#x);
} catch {
this.y = "unknown";
}
}
}

will be transformed to

JavaScript
class C {
static #x = 42;
static y;
static #_ = (() => {
try {
this.y = doSomethingWith(this.#x);
} catch {
this.y = "unknown";
}
})();
}

Because the output code includes private class properties, if you are already using other class feature plugins (e.g. @babel/plugin-transform-class-properties), be sure to place it before the others.

babel.config.json
{
"plugins": [
"@babel/plugin-transform-class-static-block",
"@babel/plugin-transform-class-properties"
]
}

Installation

npm install --save-dev @babel/plugin-transform-class-static-block

Usage

babel.config.json
{
"plugins": ["@babel/plugin-transform-class-static-block"]
}

Via CLI

Shell
babel --plugins @babel/plugin-transform-class-static-block script.js

Via Node API

JavaScript
require("@babel/core").transformSync("code", {
plugins: ["@babel/plugin-transform-class-static-block"],
});

References