@putout/plugin-remove-unused-variables

A variable is a container for a value, like a number we might use in a sum, or a string that we might use as part of a sentence.

(c) MDN

🐊Putout plugin adds ability to find and remove the variables that are declared, but:

• not passed as argument to a function;
• not used as operand in expression;

That is unused variables. Most likely it is a leftovers due to incomplete transforming of the code. Such variables take up space and gives no value so they must be removed.

☝️Remember, when you writing a transform you can skip all parts related to removing unused variables and just reuse current plugin it will make your code simpler and less error prone.

☝️No, you cannot just look at referenced and constant fields to determine if you can remove variable and here is why one of the biggest plugins exists.

Install

npm i @putout/plugin-remove-unused-variables -D

Rule

Rule remove-unused-variables is enabled by default, to disable add to .putout.json:

{
    "rules": {
        "remove-unused-variables": "off"
    }
}

❌ Example of incorrect code

const a = 'hello';
const b = 'world';

console.log(a);

✅ Example of correct code

const a = 'hello';
console.log(a);

Comparison

Linter	Rule	Fix
🐊 Putout	remove-unused-variables	✅
⏣ ESLint	no-unused-vars	❌

License

MIT