# Install ``` $ npm i @darkobits/interop-import-default ``` # Use This function is intended to gracefully address issues with the default exports of packages that may have been transpiled/bundled improperly or were simply transpiled to run in an environment that has built-in support for addressing this kind of issue. This problem can often rear its head when working in mixed CJS / ESM environments. ### Before / Ideal: ```ts import wonky from 'wonky'; // Use `wonky` as the developer intended. ``` Sometimes, based on the Node version running this code and how the code was transpiled/bundled, a package's default export may be on a property key `default` on the value imported. ### Naive TypeScript Fix: ```ts import wonkyExport from 'wonky'; const wonky = wonkyExport.default; // Now, typeof wonky is incorrect; IntelliSense is broken, and // TypeScript will throw errors. ``` Furthermore, you may run into cases where your code behaves differently in different runtime environments, especially if you are authoring a library and you don't know how your code will be transpiled by the end user. Some bundlers have built-in interop features that address this issue, but running the same code in Node will produce an error. Even worse, TypeScript can miss this error at compile-time, mistakenly thinking that the default export of a package is the value we expected it to be rather than an object with a nested `default` property. This function is designed to be used as a **runtime dependency** that will address both of these\ problems. First, it ensures your code runs the same way in both types of environments by returning the provided value as-is if it doesn't contain a `default` key. Second, it type-casts the return value as the type of the parameter provided, so TypeScript will always be happy. 🌈 ```ts import wonkyExport from 'wonky'; import { interopImportDefault } from '@darkobits/interop-import-default'; const wonky = interopImportDefault(wonkyExport); // Use `wonky` as the developer intended. ```