hash_get.js

function hash_get(key, haystack) {
    const keys = key.split('.');
    if (!Object.prototype.hasOwnProperty.call(haystack, keys[0])) {
        return null;
    }

    const matched = haystack[keys[0]];
    if (keys.length === 1) {
        return matched;
    }

    return hash_get(keys.slice(1).join('.'), matched);
}

export default hash_get;

example:

data = {
    user: {name: 'foo bar', 'email': 'foo@example.com'},
    posts: [
        { id: 1, title: 'First Article'},
        { id: 2, title: 'Second Article'}
    ]
}
hash_get('user.name', data)
// -> 'foo bar'

hash_get('posts.1.title', data)
// -> 'Second Article'