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JavaScript JavaScript Basics (Retired) Creating Reusable Code with Functions Random Number Challenge, Part II

sorin vasiliu
sorin vasiliu
6,228 Points
Posted by sorin vasiliu
sorin vasiliu
6,228 Points

Random Number Challenge, part II - Quick Question!

Hey guys, so this is my code for the RN part II :

function randomNumber( lower, upper ) {
  if ( isNaN(lower) === true || isNaN(upper) === true ) {
    throw new Error('One of the arguments is Not-A-Number! The function accepts only Numbers!');
  } else {
    var randomNum = Math.floor(Math.random() * (upper - lower + 1)) + lower;
    return document.write('<p><strong>Your number is ' + randomNum + ' !!</strong></p>');  
  }
}

Is the ""throw new Error"" part written correct ? I ask this because when I test the script with NaN it doesn't give any error messages. Not OnScreen nor in the console. It just doesn't run, that's it. Am I doing it wright ?

Second: If I call the function out 5 times, and the first call of the functions contains a NaN, then the script stops there and doesn't go to the other 4 functions below that one, is that normal? Or should it give a error message for the first and then go on to the rest...

Thanks!

Cati lucian
Cati lucian
10,119 Points
Cati lucian
Cati lucian
10,119 Points

Salut Sorin !

if ( isNaN(lower) === true || isNaN(upper) === true )

nu este necesar " === true " pt ca isNaN in sine iti intoarce boolean

3 Answers

Daniel Newman
Daniel Newman
Courses Plus Student 10,715 Points

My personal recommendation: isNaN(undefined); //true

But you can compare NaN !== NaN; // true I think you probably did not defined variables or missprint variable name or I did not get your question clear.

About this code and NaN test that never throw an exception:

if ( isNaN(lower) === true || isNaN(upper) === true )

If you pass lower as NaN it will throw you to the else statement If you will do the same with upper it will also throw you to the else statement Because ( true || false ) or ( false || true ) are both equal true

Why did not you make "console.log()" of your opperator to debug process?

sorin vasiliu
sorin vasiliu
6,228 Points
sorin vasiliu
sorin vasiliu
6,228 Points

Hi,

I'm still getting the hang of this so please bare with me if I seem not to understand.

So this is the code that works:

function randomNumber( lower, upper ) {
  if ( isNaN(lower) === true || isNaN(upper) === true ) {
    throw new Error('The app accepts only numbers! One of the args is not a number!')
  } else {
    var randomNum = Math.floor(Math.random() * (upper - lower + 1)) + lower;
    return document.write('<p><strong>Your number is ' + randomNum + ' !!</strong></p>');  
  }
}

randomNumber(1, 200);
randomNumber('two', 10);
//randomNumber('chicken', 120);
//randomNumber(' ', 90);
//randomNumber('dope', 20);
//randomNumber(' ', 20);
//randomNumber(12, 400);

Now it runs good and it gives the correct Error message in the console. With this code if ( isNaN(lower) === true || isNaN(upper) === true ) { throw new Error('The app accepts only numbers! One of the args is not a number!') } I want the program to check if either lower or upper is a NaN, and if it is, to display that error message. And the 'else' statement to run only if both the "if" statements are false. (both are numbers).

sorin vasiliu
sorin vasiliu
6,228 Points
sorin vasiliu
sorin vasiliu
6,228 Points

Dunno why I did not use console.log :P Skipped my mind that part. But I've seen the solution now and it seems to be in order. This NaN function is pretty tricky from what I've seen on the web.... Thanks for your help!

Daniel Newman
PLUS
Daniel Newman
Courses Plus Student 10,715 Points
Daniel Newman
Daniel Newman
Courses Plus Student 10,715 Points

I think you can keep your code shorter

if ( isNaN(lower) || isNaN(upper) ) {

function randomNumber( lower, upper ) {
    console.log( isNaN(lower) || isNaN(upper) );
}

randomNumber(1, 200); //false
randomNumber('two', 10); //true
randomNumber('chicken', 120); //true
randomNumber(' ', 90); //false
randomNumber('dope', 20); //true
randomNumber(' ', 20); //false
randomNumber(12, 400); //false

And if you want to throw error in case when they are both NaN you should use AND (&&) but not OR (||).

johnnyesper
johnnyesper
5,935 Points
johnnyesper
johnnyesper
5,935 Points

function getRandomNumber( lower, upper ) {

if ( isNaN(lower) === true || isNaN(upper) === true ){

throw new Error("Error dude, not a number");

} else{

return Math.floor(Math.random() * (upper - lower + 1)) + lower;

}

}

console.log( getRandomNumber( 32, 24 ) ); console.log( getRandomNumber( 1, 100 ) ); console.log( getRandomNumber( 200, 'five hundred' ) ); console.log( getRandomNumber( 1000, 20000 ) ); console.log( getRandomNumber( 50, 100 ) );