const myMap = new Map([ ['7', 'a Number Key'], [1, 'a String Key'], [false, false] ]); console.log(myMap); const capital = new Map([ ['Tokyo', 'Japan'], ['Canberra', 'Australia'], ['Kuala Lumpur', 'Malaysia'], ['Bangkok', 'Thailand'] ]); console.log(capital.size); console.log(capital.get('Kuala Lumpur')); capital.set('Dublin', 'Ireland'); console.log(capital.size); console.log(capital.get('Dublin'));