@putout/plugin-remove-useless-variables/lib/destruct/index.js

🐊Putout plugin adds ability to find and remove useless

'use strict';

const {types, operator} = require('putout');

const {
    isIdentifier,
    isRestElement,
    isAssignmentPattern,
} = types;

const {replaceWith} = operator;

const MAX_LENGTH = 20;

const getKeyLength = (a) => {
    const {key, value} = a;
    
    if (!isAssignmentPattern(value) && isIdentifier(key))
        return a.key.name.length;
    
    if (isRestElement(a) && isIdentifier(a.argument))
        return a.argument.name.length + 3;
    
    return MAX_LENGTH;
};

const sum = (a, b) => a + getKeyLength(b);

module.exports.report = (path) => {
    return `Remove useless variable '${path.node.declarations[0].init.name}'`;
};

module.exports.match = () => ({
    'const __object = __a': ({__a, __object}, path) => {
        const {parentPath} = path.parentPath;
        
        if (!parentPath)
            return false;
        
        if (!parentPath.isFunction())
            return false;
        
        if (path.node !== parentPath.node.body.body[0])
            return false;
        
        const {params} = parentPath.node;
        
        if (params.length !== 1)
            return false;
        
        const [first] = params;
        
        if (__object.properties.length > 3)
            return false;
        
        if (!isIdentifier(first))
            return false;
        
        if (__a.name !== first.name)
            return false;
        
        if (path.scope.bindings[first.name].references > 1)
            return false;
        
        const namesLength = __object.properties.reduce(sum, 0);
        
        return namesLength < MAX_LENGTH;
    },
});

module.exports.replace = () => ({
    'const __object = __a': ({__object}, path) => {
        replaceWith(path.parentPath.parentPath.get('params.0'), __object);
    },
});