How to Disable TSLint for an Unused Import in Angular

Learn how to effectively `disable TSLint` warnings for unused imports in Angular projects and streamline your development process.
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How to Disable TSLint for an Unused Import in Angular

If you're an Angular developer, you might have encountered situations where you need to import libraries solely for their side effects, rather than for using their functionality directly. In these cases, you can end up with linting errors related to unused imports, which can be quite frustrating. Fortunately, there’s a straightforward way to handle this issue. In this post, we will explore how to disable TSLint warnings for unused imports in Angular, using a specific example involving the resize-observer-polyfill library.

The Problem

Imagine you are working on a small Angular project and attempt to build it for production using the command:

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During this process, you might receive notifications about unused imports, especially if you added an import such as:

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While this import helps your project build successfully, it can lead to linting errors if ResizeObserver isn't used anywhere else in your code. For example, you might encounter an error message like this:

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This indicates that the linter has flagged the unused variable, and you need a solution to suppress this error without needing to remove the import.

The Solution: Linting Unused Imports

Step 1: Using Side-Effect Imports

If your use of resize-observer-polyfill is solely for its side effects, you can simplify your import statement. Instead of importing the default export, simply import the library directly without assigning it to a variable. Here's how you can do that:

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By doing this, you are no longer declaring a variable that the linter would flag as unused, since the import is being used for its side effects—ensuring the library gets loaded. This way, your linter should stop throwing errors related to unused imports.

Step 2: Validate Linting Configuration (Optional)

If you want to keep the original import but still want to suppress the linting error, make sure that your tslint.json configuration file is set up to accommodate the disabling of specific rules. For example:

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Step 3: Disable TSLint Locally (if necessary)

In case you want to keep your original import for any reason, you can include a comment to disable the lint rule specifically for that import. However, if the previous methods do not apply, you can try adding the following comment above your import statement:

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While many users find that importing the library as a side-effect is sufficient, this comment is a fallback for scenarios where the linter is still flagging an unused import.

Conclusion

By understanding how to handle unused imports in Angular effectively, you can focus on developing your application without getting bogged down by linting issues. Remember that directly importing a library without assigning it to a variable can often be the simplest solution for side-effect imports. For more complex scenarios, adjusting your tslint.json file or using local comments can help maintain a clean linting status in your codebase.

By following these steps, you should have a smoother development experience, keeping your codebase tidy and free of unnecessary lint errors.