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Learn how to fix the `TypeError` when calling functions across different files in Node.js using various `export` syntax.
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How to Call Two Functions with Different Export Syntax in Node.js?

In the world of JavaScript, especially when working with Node.js, proper module exports are crucial for sharing functionality across different files. However, this can sometimes lead to confusion regarding how to call functions that utilize differing export syntaxes. If you've ever encountered the TypeError: main.fun is not a function when attempting to call a function exported using a different syntax, this guide is for you.

The Problem

Imagine you've written a function in one file, and you want to use it in another file, but you're greeted with an error. Let's break down the scenario using the provided code.

Your Code Structure

Here's how your functions are organized:

main.js

[[See Video to Reveal this Text or Code Snippet]]

In main.js, you've got two exports:

A default export using the syntax module.exports = function(...).

A named export for your function fun with module.exports = {fun}, but this line is overriding the first export, which is where the issue lies.

Your Call to the Function

Now in call.js, you're trying to call the fun function:

[[See Video to Reveal this Text or Code Snippet]]

This is where the confusion leads to an error, as main.fun is undefined due to the way the exports are structured.

The Solution

To solve this issue, you need to ensure that both functions are exported properly from main.js. There are two main approaches to resolve this, depending on whether you want to stick with module.exports object or not.

1. Use Properties of module.exports

You can assign the fun function directly to the module.exports object like this:

[[See Video to Reveal this Text or Code Snippet]]

This way, you keep your initial export while still making fun() available for other files.

Updated Code Example

Here’s what your main.js file should look like after the fix:

[[See Video to Reveal this Text or Code Snippet]]

2. Using an Object for Multiple Exports

Alternatively, if your module is going to manage multiple functions, it's better practice to collect everything into a single object. Here’s how you can do that:

[[See Video to Reveal this Text or Code Snippet]]

How to Call the Function in call.js

No matter which method you choose, your call.js can remain the same:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Understanding how to properly export functions in Node.js can help avoid frustrating errors. By organizing your exports correctly, you can seamlessly share functionality between different files without running into issues like TypeError: main.fun is not a function.

When in doubt, consider how many functions you need to export and choose a strategy that keeps your code clean and maintainable. Happy coding!