【JSリファレンス】Map.prototype[@@iterator]()

const mapObj = new Map();

const obj1 = {name:"obj1"};
const obj2 = {name:"obj2"};

mapObj.set( obj1 , 100 );
mapObj.set( obj2 , 200 );

for( const [key,value] of mapObj ){
    console.log( `key.name:"${ key.name }" value:${ value }` );
}
// 結果
// key.name:"obj1" value:100
// key.name:"obj2" value:200

const mapObj = new Map( [
        [1,"A"],
        [2,"B"],
        [3,"C"]
    ]);

const valuesArray = [...mapObj];
console.log( Array.isArray( valuesArray ) ); // true
console.log( valuesArray ); // [ "A", "B", "C" ]