'use strict';

const cityPopulation = new Map();

cityPopulation.set('Shanghai', 24256800);

cityPopulation.set('Beijing', 21516000);

cityPopulation.set('Delhi', 16787941);

cityPopulation.set('Lagos', 16060303);

cityPopulation.delete('Shanghai');

if (cityPopulation.has('Beijing')) {

console.log('Beijing:', cityPopulation.get('Beijing'));

}

if (!cityPopulation.has('Shanghai')) {

console.log('no data for Shanghai');

}

console.log('size:', cityPopulation.size);

console.log('keys:', [...cityPopulation.keys()]);