JavaScript原型继承无法正常工作

Question

This is not the actual project i am working on but simple code to understand what am i doing wrong.

I have created a object named NumSelector and trying to use method validator which i have inherited using prototype. I get error "validator is not defined"

function NumSelector(num)
{
    if(validator(num))
      console.log("NUmber is positive");
    else
      console.log("Number s negative");
}

NumSelector.prototype.validator = function(num)
{
  if(num>0)
    return true;
  else
    return false;
};

Answer 1

Use this.validator() in the if condition instead of validator()

function NumSelector(num)
{
    if(this.validator(num))
      console.log("NUmber is positive");
    else
      console.log("Number s negative");
}

NumSelector.prototype.validator = function(num)
{
  if(num>0)
    return true;
  else
    return false;
};