firestore-snapshot-utils/dist/internal/maskProps.js

// NOTE: Currently only works with props that exist in the top level of the
// object
export const maskProps = (a, collection, maskKeys) => {
    if (typeof a !== 'object' || Array.isArray(a) || a === null) {
        return a;
    }
    const keys = maskKeys[collection];
    if (keys) {
        const obj = a;
        for (const key of keys) {
            if (typeof obj[key] === 'string') {
                obj[key] = obj[key].replace(/./g, '•');
            }
        }
    }
    return a;
};