arrayNb.js

class ArrayNb extends Array {
  constructor(props) {
    !!props ? super(props) : super();
  }
  push(...elements) {
    if ( [...elements].every(e => typeof e === "number") ){
      return super.push(...elements);
    } else {
      throw new Error("ArrayNb can only store numbers");
    }
  }
  populate(array) {
    if (Array.isArray(array)) {
      array.forEach(e => {
        this.push(e);
      })
    } else {
      throw new Error("ArrayNb.prototype.populate require an Array as argument");
    }
  }
}

const a = new Array();
const anb = new ArrayNb();

console.log(a);
console.log(anb);
console.log(a.push(3, 4));
console.log(anb.push(3, 4));

console.log(a)
console.log(anb)

console.log(a.join(''))
console.log(anb.join(''))

anb.populate([671,2,0]);
console.log(anb)