Is is possible to create a for-of loop without a variable?

Question

Suppose I have a function like this:

const hasAny = xs => {
  for (const x of xs) {
    return true;
  }

  return false;
};

eslint will complain that x is not used, and indeed it isn't.

Can I write a for-of loop that does not declare any variables?

Answer 1

According to ESLint issue #2173, you can set a comment to ignore the unused variable. For that, use the following code:

var some_unused_variable; // eslint-disable-line no-unused-vars

A community member of ESLint also states:

We now have a varsIgnorePattern option available for this use case (best suited for ignoring specific unused variable names or patterns across all your files).

And documentation states:

The varsIgnorePattern option specifies exceptions not to check for usage: variables whose names match a regexp pattern. For example, variables whose names contain ignored or Ignored.

Examples of correct code for the { "varsIgnorePattern": "[iI]gnored" } option:

/*eslint no-unused-vars: ["error", { "varsIgnorePattern": "[iI]gnored" }]*/

var firstVarIgnored = 1;
var secondVar = 2;
console.log(secondVar);