Get JavaScript object nested attributes

index.js

function propertiesToArray(obj) {
    const isObject = val => typeof val === 'object' && !Array.isArray(val);
    const isArray = val => Array.isArray(val);

    // Format output keys
    const addDelimiter = (a, b, type) => a ? `${a}.[${b}: ${type}]` : `[${b}: ${type}]`;

    const paths = (obj = {}, head = '') => {
        return Object.entries(obj).reduce((product, [key, value]) => {
            let fullPath = addDelimiter(head, key, typeof value);

            // If attribute is an array, get attributes of first item.
            // This is not exactly true, but an assumption
            // Remove the if in case you don't want to introspect arrays.
            if (isArray(value)) {
                return product.concat(paths(value[0], fullPath));
            }

            return isObject(value) 
                ? product.concat(paths(value, fullPath))
                : product.concat(fullPath);
        }, []);
    }

    return paths(obj);
};