testPerformanceOnGettingSize.js

const objectMaker = (_size)=>{
    //create an object with size of _size
    let obj = {}
    for(let i=0; i<_size; i++){
        obj[i.toString()] = i
    }
    return obj
}

const mapMaker = (_size)=>{
    //create a map with size of _size
    let map = new Map();
    for(let i=0; i<_size; i++){
        map.set(i.toString(), i)
    }
    return map
}

const checkInterval = (cb) => {
    //checkInterval in millionth second of conducting callback
    let beginning = Date.now();
    cb()
    let ending = Date.now();
    return ending-beginning
}

let obj1 = objectMaker(100000);
let map1 = mapMaker(100000);

let obj1Time = checkInterval(()=>{
    //measuring elapsed time of getting size of an object
    console.log('object size', Object.keys(obj1).length )
    return Object.keys(obj1).length;
})

let map1Time = checkInterval(()=>{
    //measuring elapsed time of getting size of an map
    console.log('map size', map1.size)
    return map1.size
});
console.log('map1Time', map1Time);
console.log('obj1Time', obj1Time);