NOTE: This plugin is included in @babel/preset-env, in ES2020

Example?

In

JavaScript

var foo = object.foo ?? "default";

Out

JavaScript

var _object$foo;

var foo =
  (_object$foo = object.foo) !== null && _object$foo !== void 0
    ? _object$foo
    : "default";

NOTE: We cannot use != null here because document.all == null and document.all has been deemed not "nullish".

Installation?

• npm
• Yarn
• pnpm

pnpm add --save-dev @babel/plugin-proposal-nullish-coalescing-operator

Usage?

With a configuration file (Recommended)?

babel.config.json

{
  "plugins": ["@babel/plugin-proposal-nullish-coalescing-operator"]
}

Via CLI?

Shell

babel --plugins @babel/plugin-proposal-nullish-coalescing-operator script.js

Via Node API?

JavaScript

require("@babel/core").transformSync("code", {
  plugins: ["@babel/plugin-proposal-nullish-coalescing-operator"],
});

Options?

loose?

boolean, defaults to false.

When true, this transform will pretend document.all does not exist, and perform loose equality checks with null instead of strict equality checks against both null and undefined.

?? Consider migrating to the top level noDocumentAll assumption.

babel.config.json

{
  "assumptions": {
    "noDocumentAll": true
  }
}

Example?

In

JavaScript

var foo = object.foo ?? "default";

Out

JavaScript

var _object$foo;

var foo = (_object$foo = object.foo) != null ? _object$foo : "default";

You can read more about configuring plugin options here

References?

• Proposal: Nullish Coalescing