[@babel/preset-typescript] Namespace alias (native TS feature) is not supported

Bug Report

• I would like to work on a fix!

import RenamedModule = OriginalModule is native Typescript’s feature for creating module alias but @babel/preset-typescript does not allow this syntax.

Current behavior

@babel/preset-typescript gives an error.

Error: `import =` is not supported by @babel/plugin-transform-typescript
Please consider using `import <moduleName> from '<moduleName>';` alongside Typescript's --allowSyntheticDefaultImports option.

Input Code

declare module LongNameModule {
  export type SomeType = number;
}
import AliasModule = LongNameModule;

const some: AliasModule.SomeType = 3;
console.log(some);

Expected behavior

It outputs: 3.

Using tsc and ts-node, it is compiled as expected.

Babel Configuration (babel.config.js, .babelrc, package.json#babel, cli command, .eslintrc)

• Filename: babel.config.js

{
  presets: [
    [
      '@babel/env',
      {
        modules: false,
        targets: {
          esmodules: true,
        },
      },
    ],
    [
      '@babel/typescript',
      {
        allowDeclareFields: true,
      },
    ],
  ],
};

Environment

• Babel version: v7.12.3
• Node/npm version: Node 14/yarn 1.22.10
• OS: alpine linux (in docker)
• Monorepo: no
• How you are using Babel: cli

Possible Solution

I have no idea.

[nicolo-ribaudo]

This is something that we can support. When we wrote those docs, what we wanted to disallow was import foo = require("...") and export =. import foo = bar is a different feature that has nothing to do with ESM (it just re-uses the keyword).

[orty]

Hi,

Is there any news regarding this ? I looked around for a plugin to use as a workaround until Babel support namespace aliases but no luck 😦