How to disable warn about some unused params, but keep "@ typescript-eslint / no-unused-vars " rule

In environments where TypeScript and ESLint are used together for code quality control, the @typescript-eslint/no-unused-vars rule is employed to detect unused variables. This is highly beneficial for maintaining code cleanliness and maintainability. However, in certain scenarios, it may be necessary to disable warnings for specific unused parameters without fully disabling this rule.

Several approaches can achieve this:

1. Using ESLint Comments

The most straightforward method is to temporarily disable the rule for specific lines or files using ESLint's control comments. For example:

typescript
// eslint-disable-next-line @typescript-eslint/no-unused-vars
const [value, setValue] = useState(0);

This comment temporarily suppresses the no-unused-vars rule check for the subsequent line. It is ideal for isolated lines or small code segments. For disabling the rule across an entire file, add the comment at the top:

typescript
/* eslint-disable @typescript-eslint/no-unused-vars */

2. Modifying the ESLint Configuration

Another approach involves adjusting the behavior of the @typescript-eslint/no-unused-vars rule in the ESLint configuration file. You can leverage the argsIgnorePattern or varsIgnorePattern options to define which parameter or variable names should be exempt from checks. For instance, if your coding convention prefixes unused parameters with _, configure it as follows:

json
{
  "rules": {
    "@typescript-eslint/no-unused-vars": ["error", { "argsIgnorePattern": "^_" }]
  }
}

This configuration ensures that all parameters starting with _ are excluded from the no-unused-vars rule.

3. Using TypeScript Compiler Options

TypeScript's compiler also provides similar functionality; setting noUnusedParameters to false can ignore unused parameters at the compilation level. However, this approach is global and less flexible than ESLint-based solutions.

Example

Consider the following code snippet where a function's parameter is unused within its body:

typescript
function example(_unusedParameter: string, usedParameter: number) {
    console.log(usedParameter);
}

If your ESLint configuration includes the argsIgnorePattern setting described above, _unusedParameter will not trigger a no-unused-vars warning even when unused.

Conclusion

The optimal method depends on your specific requirements and project setup. For temporary or single-line adjustments, using ESLint comments offers the quickest solution. For systematic changes, modifying the ESLint rule configuration is more appropriate. This approach enhances code readability and maintainability without compromising essential rules.