Get rid of 'is defined but never used' in function parameter

Question

I am getting the error/warning from ESLint that 'd' is declared but never used, however I need this type declaration in function parameter to avoid subsequent TypeScript errors. Is there a way of solving this problem/warning except changing the rules in .eslintrc.json file for no-unused-vars?

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• jonrsharpe: You need to use the TypeScript version of the rule, ESLint's rules aren't aware of types: github.com/typescript-eslint/typescript-eslint/blob/master/…

Answer 1

In your .eslintrc.json add "no-unused-vars": ["error", { "argsIgnorePattern": "^_" }] to "rules". Mine looks like this:

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

Now you should be able to add an underscore to the start of your variable declarations and it should avoid the error message.

Ex:

const myFunc = (c, b) => {} would be const myFunc = (_c, _b) => {}

You can also take a look ate argsignorepattern in the ESLint documentation.

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I believe if you are using the typescript you might also have to add "@typescript-eslint/no-unused-vars": ["error", { "argsIgnorePattern": "^_" }]"

• spatak: Thank you a lot! Actually 'no-unused-vars': 1 just replaces the error with warning but following the link you mentioned and setting ["error", { "argsIgnorePattern": "^_" }] helped!
• Hozeis: Glad I could help.
• Hozeis: @spatak Did you just set "rules": {"no-unused-vars": ["error", { "argsIgnorePattern": "^_" }],} ?
• spatak: yes. I added it above all of my over rules
• Michael Sherris Caley: Great solution, I went with "no-unused-vars": ["error", { "argsIgnorePattern": "^_" }]

Answer 2

i think this is the shortest answer

//.eslintrc.json
...
"rules": {
 "no-unused-vars": "off",
 "@typescript-eslint/no-unused-vars": "error",
 },
...