Why is typeof x never 'number' when x comes from the prompt function?

Question

I\'m having trouble getting the first function (below) to work correctly. I want it to ask for the age of the user with two possible outcomes. If the user enters the correct

Answer 1

The other answers are showing you that prompt() (almost) always returns a string. You'll need to parseInt the response before you can check it for your age range. But I think your while-loop conditional is throwing you off. Also you need to parseInt() on the prompt a second time, inside your while loop. Try it like this:

let age_entered = prompt("Enter Your Age:");
age_entered = parseInt(age_entered); 

while (age_entered <= 0 || Number.isNaN(age_entered)) {
   alert("You entered an incorrect value. Please enter correct age.");
   age_entered = prompt("Enter Your Age:");
   // do parseInt again
   age_entered = parseInt(age_entered); 
}

Notice we use Number.isNaN(age_entered). This is a more robust way to determine if a value is a number than comparing with typeof. See this doc here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN