keys < Map < JavaScript

The keys() method of the Map object returns an iterator object that contains all of the keys of the key/value pairs in insertion order.

    
    const officers = new Map([
        ['president', 'Jeff'],
        ['secretary', 'Adam'],
        ['treasurer', 'Anne']
    ]);

    // iterator object
    const officersKeys = officers.keys();

    for (const key of officersKeys) {
      console.log(key);
    }
    // "president"
    // "secretary"
    // "treasurer"