I want to create some utility functions that use the “any” type, and it seems that using unknown or another type is not a solution. What should I do?

In the TypeScript project with typescript eslint I am working on, using the “any” type is prevented via “no-explicit-any” and using comments such as “ts-ignore” to allow “any” in code prevent via “ban-ts-comments”. I want to create some utility functions that use the “any” type, and it seems that using unknown or another type is not a solution. What should I do?

While “no-explicit-any” and “ban-ts-comments” are in place to enforce type safety, there are a few approaches you can consider for creating utility functions using the “any” type in your specific situation:

1. Opt-out for specific files:

• .eslintrc.json: If absolutely necessary, you can configure ESLint to ignore specific files or directories containing your utility functions. This allows using “any” in those files while maintaining type safety in the rest of the project. However, use this approach with caution as it weakens the type system’s benefits.

{
  "rules": {
    "@typescript-eslint/no-explicit-any": "off" // disable in specific files/directories
  }
}

2. Create a separate TypeScript project:

• Consider creating a separate, smaller TypeScript project specifically for your utility functions. This allows using “any” without compromising the type safety of your main project. You can then import the necessary functions from the utility project into your main codebase.

3. Explore alternative approaches:

• While not ideal, could you explore alternative ways to achieve the functionality of your utility functions without relying on “any”? This might involve:
  • Refactoring the code to use generic types, conditional types, or type assertions more strategically.
  • Revisiting the design of the functions to avoid the need for such broad typing.

4. Evaluate the necessity of “any”:

• Critically evaluate whether using “any” is truly unavoidable. Often, the “unknown” type can be a safer alternative, allowing some type checking while acknowledging the unknown nature of the data.

Remember, using “any” should be a last resort due to the potential drawbacks it introduces. It’s essential to weigh the benefits against the risks before making a decision.

It’s also crucial to document your reasoning clearly in the code if you choose to opt-out of type safety for specific functions. This helps maintain code clarity and informs future developers about the trade-offs made.

“Opt-out for specific files” seems like the correct solution. How do I apply this to a specific file and/or a specific directory?

You have two options to apply the “opt-out” approach for specific files or directories:

1. Using overrides in your .eslintrc.json:

• This approach allows you to configure different ESLint rules for specific parts of your project. Here’s an example:

{
  "overrides": [
    {
      "files": ["src/utils/*.ts"], // Target all files in the "utils" directory
      "rules": {
        "@typescript-eslint/no-explicit-any": "off" // Disable "no-explicit-any" for these files
      }
    },
    {
      "files": ["src/specific-file.ts"], // Target a specific file
      "rules": {
        "@typescript-eslint/no-explicit-any": "off" // Disable "no-explicit-any" for this file
      }
    }
  ]
}

In this example, the first override disables “no-explicit-any” for all TypeScript files within the “src/utils” directory, while the second disables it for the specific file “src/specific-file.ts”.

2. Using a dedicated .eslintignore file:

• While not explicitly recommended due to potential conflicts, you can create a .eslintignore file in the root directory of your project. This file allows you to list files or directories to be ignored by ESLint. However, prioritize using overrides over .eslintignore to maintain clear configuration and avoid unintended consequences.

# Ignore the "utils" directory and all its files
src/utils/

# Ignore a specific file
src/specific-file.ts