Скачать или смотреть How to Require Local Javascript Files with Rails 6 and Webpacker

Learn how to properly require local JavaScript files in your Rails 6 application using Webpacker. This guide breaks down the solution step-by-step, ensuring seamless integration of dependencies.
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This video is based on the question https://stackoverflow.com/q/62604372/ asked by the user 'max pleaner' ( https://stackoverflow.com/u/2981429/ ) and on the answer https://stackoverflow.com/a/62605487/ provided by the user 'cdadityang' ( https://stackoverflow.com/u/12543970/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Challenge of Requiring Local JavaScript Files in Rails 6 with Webpacker

If you're working with Rails 6 and utilizing Webpacker, you might encounter situations where you need to load local JavaScript files that depend on one another. This might seem straightforward, but many find themselves stumped when their attempts lead to frustrating errors. One common issue arises when trying to require a JS file from a different directory and seeing errors such as Cannot find module 'lib/helper_functions'.

In this guide, we'll explore how to resolve this issue step-by-step. We will discuss how you can effectively require local JavaScript files in your Rails 6 application, ensuring all dependencies are properly structured and accessible.

The Scenario

Let’s illustrate with a practical example. You have a CoffeeScript file located at:

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

You are including this file in your HTML using the following tag:

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

Within the post_form.js.coffee, you aim to require a helper function from another file located at:

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

The attempt to load this helper file might look like this:

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

However, you encounter the error indicating that the module cannot be found, which can halt your development progress.

The Solution: How to Properly Require JavaScript Files

The key to resolving your issue lies in how you structure the require statements concerning the file paths. Here’s how to properly require your local JavaScript files:

Step 1: Modify Your Import Statement

Instead of using a relative path that doesn’t work for your current directory structure, you need to adjust the path to be relative to the post_form.js.coffee file itself.

This means changing your require to:

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

This modification points the require action to look one directory up (../) and then into the lib folder where your helper_functions.js.coffee file resides.

Step 2: Ensure Your Helper Function is Exported Properly

In your helper_functions.js.coffee, make sure you are exporting your methods correctly. For instance:

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

This setup allows other files to access the UsefulMethod when they require helper_functions.

Final Code Overview

Here’s what both files will look like after the modification:

app/javascript/packs/post_form.js.coffee

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app/javascript/lib/helper_functions.js.coffee

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

Conclusion

By ensuring that you specify the correct relative path for your requires, you can easily manage dependencies between local JavaScript files in a Rails 6 application using Webpacker. This approach not only fixes the module not found error but also helps you maintain a clean and efficient coding structure.

So if you ever find yourself facing the same challenge, remember to check your paths and ensure they're correctly referencing the files as needed. Happy coding!