what `new Array(n)` does

newArrayInES6.js

let newArray = (n) => {
    let o = Object.create(null);
    Object.setPrototypeOf(o, Array.prototype);
    Object.defineProperty(o, 'length', {value:n});
    return o;
}

// let a = newArray(2);                                                         
// console.log((a).map)                                                         
// console.log((a).map($=>"hello"))                                             
// console.log(Array.from(a).map($=>"hello"))                                   
// for (let k in a) { console.log('a[' + k + '] = ', a[k]); }