Instantiating an object with boolean false gives unexpected result [closed]

Why does the following code return 'the value of bool1 is incorrect':

class NoDefaultParams {
  constructor(num1, num2, num3, string1, bool1) {
    this.num1 = num1;
    this.num2 = num2;
    this.num3 = num3;
    this.string1 = string1;
    this.bool1 = bool1;
  }
  calculate() {
    if (this.bool1) {
      console.log(this.string1, this.num1 + this.num2 + this.num3);
      return;
    }
    return 'The value of bool1 is incorrect';
  }
}

var fail = new NoDefaultParams(1, 2, 3, "test", false);

console.log(fail.calculate());

And why does the following code return the calculate() method:

class NoDefaultParams {
  constructor(num1, num2, num3, string1, bool1) {
    this.num1 = num1;
    this.num2 = num2;
    this.num3 = num3;
    this.string1 = string1;
    this.bool1 = bool1;
  }
  calculate() {
    if (this.bool1) {
      console.log(this.string1, this.num1 + this.num2 + this.num3);
      return;
    }
    return 'The value of bool1 is incorrect';
  }
}

var fail = new NoDefaultParams(1, 2, 3, "test", true);

console.log(fail.calculate());

Are they both not boolean values? the if statement is just looking for the property whether it is true or false correct? What am I missing? Why can't the boolean argument be false?

Via Active questions tagged javascript - Stack Overflow https://ift.tt/tpTR7Uw