@putout/plugin-remove-unused-variables

@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. Merged with @putout/plugin-variables.

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