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JavaScript

Posted by Allen Palacios
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Allen Palacios
Full Stack JavaScript Techdegree Student 5,810 Points

Can I use &&?

I used && on my code and it worked. I'm wondering if that right or not?

// declare program variables
var num1;
var num2;
var message;
// announce the program
alert("Let's do some math!");

// collect numeric input
num1 = prompt("Please type a number");
num1 = parseFloat(num1);
num2 = prompt("Please type another number");
num2 = parseFloat(num2);

if( num2 === 0 ) {
  alert( "Dude it's 0, you can't divide by 0. Reload and try again.");
}else if( isNaN(num1 && num2) ) {
  alert( "At least one of these values is not a number. Reload and try again." );
} else {
  // build an HTML message
  message = "<h1>Math with the numbers " + num1 + " and " + num2 + "</h1>";
  message += num1 + " + " + num2 + " = " + (num1 + num2);
  message += "<br>";
  message += num1 + " * " + num2 + " = " + (num1 * num2);
  message += "<br>";
  message += num1 + " / " + num2 + " = " + (num1 / num2);
  message += "<br>";
  message += num1 + " - " + num2 + " = " + (num1 - num2);

  // write message to web page
  document.write(message);
}

1 Answer

Robert Manolis
STAFF
Robert Manolis
Treehouse Guest Teacher
Robert Manolis
Robert Manolis
Treehouse Guest Teacher

Hi Allen, yes, you can definitely use the and operator, but I don't think you'll get the evaluation you're looking for with the way you have it set up. Rather than this: isNaN(num1 && num2), you most likely want this: 

isNaN(num1) && isNaN(num2)

Hope that helps. :thumbsup: