How to Dynamically Get a Function in JavaScript and ReactJS

Learn how to use dynamic imports in JavaScript and ReactJS by understanding how to retrieve configurations based on parameters.
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Understanding Dynamic Imports in JavaScript

When working on software projects, developers often face the need to dynamically import modules based on certain conditions or parameters. This flexibility is crucial for improving code organization and reducing initial load times. However, it can sometimes lead to challenges, especially when the expected functionality does not work as anticipated.

In this guide, we'll explore a scenario involving dynamic imports in JavaScript, specifically within ReactJS, and provide a solution for a common issue developers encounter.

The Problem

Imagine you have three different configuration files: newConfig, historyConfig, and draftConfig. Each file exports a config1 object. Your goal is to import these configurations dynamically based on a specific parameter.

For example, you want to import the configuration corresponding to a currentType and currentMode you provide:

Configuration Files

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The Dynamic Import Issue

You have the following function that aims to achieve this:

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However, you encounter a problem when you attempt to use a variable in the import statement. Here's the critical part of the error:

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This fails, while the static import works fine:

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The Root Cause

The issue arises from how packaging tools, like webpack, handle dynamic imports. These tools do not analyze paths that contain variables. They are optimized to work with static string paths. When you use a variable in the import statement, the tool cannot determine which file to include during the build process.

Important Points to Note

Static Import: Works because the path is known at compile-time.

Dynamic Import with Variable: Fails because the path is not defined until runtime, which the build tool cannot resolve.

Solution: How to Make It Work

To make dynamic imports work correctly, you can utilize one of the following strategies:

1. Use Relative Paths

In many cases, you can construct a relative path dynamically instead of relying on absolute paths with patterns. Ensure that the path is correct relative to where the files are located in your project structure.

2. Add File Extension

Another point to consider is to make sure you specify the file extension when dynamically importing:

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3. Maintain a Mapping Object

If the configurations are relatively simple and predictable, you can map currentType and currentMode to specific imports:

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Conclusion

Dynamic imports in JavaScript and ReactJS can elevate your code efficiency but require understanding how build tools process them. By recognizing the limitations when using variables in import paths and utilizing strategies like relative paths and mapping, you can effectively manage configuration imports without running into errors. Embrace these practices, and you'll enhance your application's capability in handling imports dynamically.