How to Include Comments in JSON Files

JSON, which stands for JavaScript Object Notation, is a way computers use to share and store information that’s easy for people to read and write. Even though it’s simple and useful, JSON doesn’t let you add comments directly in the data, which can make it hard for people working together to understand what each part of the data is supposed to do. In this article, we’re going to talk about how you can add notes and explanations to your JSON files in different ways, so your projects can be clearer and everyone can work better together.

Understanding the JSON Format

Before we explore solutions, it’s important to understand why JSON was designed without comment support. JSON’s primary goal is to be a simple data format with minimal complexity. Comments, while useful for developers, are not data per se and can complicate parsing processes, especially when JSON data is consumed by multiple systems and platforms.

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Strategies for Commenting in JSON

1. Using External Documentation

The most straightforward approach to circumvent the lack of comments in JSON is to maintain an external documentation file. This file can detail the structure, purpose, and usage of various elements within your JSON file. Tools like Swagger for API documentation or README files in your repositories can serve this purpose well, ensuring that anyone working with the JSON files can understand their context and structure.

2. Adopting a Naming Convention

Another effective strategy is to use meaningful names for your keys that can act as implicit comments. For example, instead of naming a key simply as “threshold”, you might name it “thresholdInSecondsForSessionTimeout”, which offers much more context about what the value represents.

{
  "thresholdInSecondsForSessionTimeout": 30
}

3. Incorporating Meta-Keys

A common workaround is to include keys in your JSON that act as comments. These keys, often prefixed with an underscore or a specific keyword like “_comment”, can provide necessary context. For example:

{
  "_comment": "This setting defines the timeout threshold in seconds",
  "timeoutThreshold": 30
}

It’s important, however, to ensure that your application or any applications that consume this JSON can safely ignore these meta-keys.

4. Utilizing Preprocessing Tools

For complex projects, you might consider using preprocessing tools that strip out comments from your JSON files before they are used in a production environment. This approach allows developers to include comments in their working files for clarity and collaboration. Tools like JSONC or JSON5 extend the JSON format to support comments, which are then removed during the build or deployment process, ensuring compatibility with strict JSON parsers.

5. Leveraging JSON Schemas

JSON Schema provides a powerful way to document your JSON format in a machine-readable form. While not a direct way to include comments in JSON, it allows you to define the structure, types, and descriptions of your JSON elements in a separate file. This not only helps with validation but also serves as detailed documentation for your JSON files.

Conclusion

While JSON’s lack of native comment support can initially seem like a hindrance to clarity and collaboration, various strategies can be employed to effectively document and describe your JSON files. Whether through external documentation, meaningful naming conventions, meta-keys, preprocessing tools, or JSON Schema, it’s possible to maintain the readability and maintainability of your JSON files. Adopting these practices ensures that your data remains comprehensible and accessible to all members of your team, fostering better understanding and collaboration in your projects.