Task 3 for constructor function

gistfile1.txt

const Accumulator = function (startingValue) {
  this.value = startingValue;

  this.read = function () {
    this.value += +prompt('Insert new value (task 3)', 0);
  }
};

const accumulator = new Accumulator(1);
accumulator.read();
accumulator.read();
alert(`Текукщее значение: ${accumulator.value}`);