@babel/plugin-syntax-optional-chaining

What is @babel/plugin-syntax-optional-chaining?

The @babel/plugin-syntax-optional-chaining package allows Babel to parse and understand the optional chaining syntax. Optional chaining (`?.`) permits reading the value of a property located deep within a chain of connected objects without having to expressly validate that each reference in the chain is valid. The `?.` operator functions similarly to the `.` chaining operator, except that instead of causing an error if a reference is nullish (`null` or `undefined`), the expression short-circuits with a return value of `undefined`. This simplifies accessing values through connected objects when there's a possibility that a reference may be missing.

What are @babel/plugin-syntax-optional-chaining's main functionalities?

Optional Property Access

This feature allows safe access to nested object properties without having to check each level of the object to ensure it exists. If any reference is nullish, the expression evaluates to `undefined` instead of throwing an error.

const streetName = user?.address?.street;

Optional Method Calls

Enables calling a method on an object only if the object exists; otherwise, it returns `undefined`. This is useful for calling methods on objects that may not be initialized.

const length = users?.length;

Optional Bracket Notation

Similar to optional property access, but with the ability to access properties using bracket notation. This is useful when property names are dynamically determined.

const lastName = user?.['name']?.['last'];

Other packages similar to @babel/plugin-syntax-optional-chaining

@babel/preset-env

While not exclusively focused on optional chaining, @babel/preset-env includes support for it among other JavaScript features. This preset allows you to use the latest JavaScript without needing to micromanage which syntax transforms (or polyfills) are needed by your target environment(s). It's more comprehensive but heavier than using a specific plugin for optional chaining.

typescript

TypeScript, a superset of JavaScript, includes support for optional chaining natively. When compiling TypeScript code to JavaScript, the TypeScript compiler can transform optional chaining syntax into equivalent JavaScript that works in environments not supporting the syntax natively. This offers a broader solution for adopting modern JavaScript features, including but not limited to optional chaining.

README

@babel/plugin-syntax-optional-chaining

Allow parsing of optional properties.

Installation

npm install --save-dev @babel/plugin-syntax-optional-chaining

Usage

Via .babelrc (Recommended)

.babelrc

{
  "plugins": ["@babel/plugin-syntax-optional-chaining"]
}

Via CLI

babel --plugins @babel/plugin-syntax-optional-chaining script.js

Via Node API

require("@babel/core").transform("code", {
  plugins: ["@babel/plugin-syntax-optional-chaining"]
});