Is there an eslint rule for detecting unused class properties?

user_10875364 0
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I am working with an Angular project and my ESLint setup does not detect when a private class variable is unused, e.g.

@Component{...}
export class ExampleComponent {
  private exampleProperty: string
}

The private property above - exampleProperty will not be highlighted with the current ESLint setup that I have.

My .eslintrc.json:

{
  "root": true,
  "ignorePatterns": ["projects/**/*"],
  "overrides": [
    {
      "files": ["*.ts"],
      "parserOptions": {
        "project": ["tsconfig.json", "e2e/tsconfig.json"],
        "createDefaultProgram": true
      },
      "env": { "browser": true, "jest": true },
      "extends": [
        "eslint:recommended",
        "plugin:@angular-eslint/recommended",
        "plugin:@angular-eslint/template/process-inline-templates",
        "plugin:@typescript-eslint/recommended"
      ],
      "rules": {
        "@angular-eslint/component-selector": [
          "error",
          { "prefix": "app", "style": "kebab-case", "type": "element" }
        ],
        "@angular-eslint/no-host-metadata-property": "off",
        "@typescript-eslint/ban-ts-comment": "off",
        "@typescript-eslint/ban-types": "off",
        "@typescript-eslint/explicit-module-boundary-types": "off",
        "@typescript-eslint/no-explicit-any": "off",
        "@typescript-eslint/no-unused-vars": [
          "error",
          { "argsIgnorePattern": "^_" }
        ],
        "no-case-declarations": "off",
        "no-console": ["error", { "allow": ["warn", "error"] }],
        "no-prototype-builtins": "off",
        "no-unused-vars": "off"
      }
    },
    {
      "files": ["*.html"],
      "extends": ["plugin:@angular-eslint/template/recommended"],
      "rules": {}
    }
  ]
}

How can I get the linter to pick this up?

typescript-eslint angular eslint typescript
1 Answers

You can get TypeScript to pick this up for you, by turning on the noUnusedLocals option in tsconfig.json. ("Locals" apparently includes unused private properties, which are after all local to the class.)

Here's a playground with that class with the option turned on, which gives the error:

'exampleProperty' is declared but its value is never read.(6133)

(I added a constructor and set the property, just so the error isn't mixed with / obscured by the error about it not being initialized.)

user_1572470
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