forEach < Map < JavaScript

The forEach() method of the Map object executes a provided function once per each key/value pair in the map, in insertion order.

    
    const things = new Map([
      ['Detroit', 'Michigan'],
      ['year_founded', 1701],
      [{}, 'empty_object'],
      ['leadership', {"mayor":"Mike Duggan"}],
      ['future', undefined],
    ]);

    things.forEach((value, key) =>
        console.log(`${key} = ${value}`)
    );

    // "Detroit = Michigan"
    // "year_founded = 1701"
    // "= empty_object"
    // "leadership = [object Object]"
    // "future = undefined"