@putout/plugin-convert-for-in-to-for-of/lib/positive/index.js

🐊Putout plugin adds ability to convert for-in to for-of

'use strict';

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

const {
    contains,
    getTemplateValues,
} = operator;

module.exports.report = () => `for-of should be used instead of for-in`;

module.exports.match = () => ({
    'for (__a in __b) __body': ({__a, __b, __body}) => {
        const declaration = getTemplateValues(__a, 'var __a');
        
        if (!declaration.__a)
            return false;
        
        const {name} = declaration.__a;
        
        return contains(__body, [
            `if (${__b.name}.hasOwnProperty(${name})) __body`,
        ]);
    },
});

module.exports.replace = () => ({
    'for (__a in __b) __body': ({__b, __body}) => {
        const [first] = __body.body;
        const condition = getTemplateValues(first, 'if (__b.hasOwnProperty(__a)) __body');
        const {code} = generate(condition.__body);
        
        return `for (const ${condition.__a.name} of Object.keys(${__b.name})) ${code}`;
    },
});