How to Maintain Default Exports Compatibility after Babel 6\'s Export Behavior Shift?

Babel 6 Export Behavior: Navigating the Shift in Default Exports

Babel 6 has introduced a significant change in the way it handles default exports in certain scenarios. Previously, Babel automatically added the line module.exports = exports["default"], which enabled access to default exports via the CommonJS require function. However, with the advent of Babel 6, this behavior has been deprecated.

This change has created a compatibility issue for code that relies on the previous CommonJS export mechanism. Users are now required to explicitly access default exports using the .default property, as seen below:

<code class="python">var foo = require('./foo').default;
// use foo</code>

While this modification may not seem drastic, it presents challenges for legacy code that expected the CommonJS export format. The article explores potential solutions for maintaining compatibility with the old export behavior without manually fixing each instance:

Compatibility Options:

• Direct Use of CommonJS: Consider using CommonJS directly, instead of relying on Babel's CommonJS interoperability feature.
• Use Babel Plugin: Utilize the @babel/preset-env plugin with the loose option, which allows for compatibility with previous CommonJS export behavior.

It's important to note that the removal of the automatic module.exports = exports["default"] line was intentional. It aimed to prevent confusion and adherence to invalid ES6 semantics. The article highlights an example where a default export of an object with a named property would result in unexpected behavior when loading the module using CommonJS interoperability.

For users who wish to maintain both named and default exports, they can explicitly add module.exports = exports["default"] to their module code. However, this approach may not be ideal in all cases, especially when integrating with existing code that relies on the old export behavior.

The article concludes by acknowledging the possibility of misunderstanding the ES6 module system, which can lead to confusion when Babel's behavior changes. It emphasizes the importance of understanding the underlying principles to adapt effectively to such updates in Babel's functionality.

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