JavaScript Prime Number Checker

Question

JavaScript Prime Number Checker

What could be the reason for this code not printing anything to the console? Here is a breakdown of the issue:

Create a JavaScript function that takes an array with an integer N and checks if the given N is a prime number (meaning it is only divisible by itself and 1 without any remainder).

var n = ['2'];

function isPrime(n) {

    if (n < 2) {
      return false;
    }

    var isPrime = true;

    for(var i = 2; i < Math.sqrt(n); i += 1) {
      if (n % i === 0) {
        isPrime = false;
      }
    }

    return isPrime;
}

return isPrime(n);

javascript numbers

Answer 1

Answer №1

Your code has a couple of mistakes that need to be fixed.

Firstly, it is important to iterate through every integer between 2 and Math.sqrt(n) inclusively. Otherwise, your current code will return true for 4.

Since it seems like this code is not within a function, you should remove the return from return isPrime(n), and instead use a function that displays the return value of the function, such as alert or console.log.

Keep in mind that n is actually an array, not a number. To fix this, either convert n into a number or call the function with isPrime(n[0]).

The corrected version of the code is shown below:

var n = 2;

function isPrime(n) {

    if (n < 2) {
      return false;
    }

    var isPrime = true;

    for(var i = 2; i <= Math.sqrt(n); i += 1) {
      if (n % i === 0) {
        isPrime = false;
      }
    }

    return isPrime;
}

alert(isPrime(n));

Note: You can replace n += 1 with n++ for the same result.

Answer 2

Your code has a couple of mistakes that need to be fixed.

Firstly, it is important to iterate through every integer between 2 and Math.sqrt(n) inclusively. Otherwise, your current code will return true for 4.

Since it seems like this code is not within a function, you should remove the return from return isPrime(n), and instead use a function that displays the return value of the function, such as alert or console.log.

Keep in mind that n is actually an array, not a number. To fix this, either convert n into a number or call the function with isPrime(n[0]).

The corrected version of the code is shown below:

var n = 2;

function isPrime(n) {

    if (n < 2) {
      return false;
    }

    var isPrime = true;

    for(var i = 2; i <= Math.sqrt(n); i += 1) {
      if (n % i === 0) {
        isPrime = false;
      }
    }

    return isPrime;
}

alert(isPrime(n));

Note: You can replace n += 1 with n++ for the same result.

Answer 3

Answer №2

To start, the variable n is an array that you need to access the first element of and convert it into a number.

Consider changing this line:

return isPrime(n);

To this new version:

return isPrime(parseInt(n[0],10));

Additionally, make sure to adjust your for-loop condition like so:

for(var i = 2; i <= Math.sqrt(n); i += 1) { //note that i should not be <= Math.sqrt(n)

Answer 4

To start, the variable n is an array that you need to access the first element of and convert it into a number.

Consider changing this line:

return isPrime(n);

To this new version:

return isPrime(parseInt(n[0],10));

Additionally, make sure to adjust your for-loop condition like so:

for(var i = 2; i <= Math.sqrt(n); i += 1) { //note that i should not be <= Math.sqrt(n)

Answer 5

Answer №3

Here are a few minor mistakes:

var x = 2;//<--unnecessary to store x in an array

function isPrime(x) {
if (x < 2) {
    return false;
}
var prime = true;

for(var j = 2; j < Math.sqrt(x); j += 1) {
    if (x % j === 0) {
        prime = false;
    }
}
return prime;
}

isPrime(x);//<--no need for "return"

Answer 6

Here are a few minor mistakes:

var x = 2;//<--unnecessary to store x in an array

function isPrime(x) {
if (x < 2) {
    return false;
}
var prime = true;

for(var j = 2; j < Math.sqrt(x); j += 1) {
    if (x % j === 0) {
        prime = false;
    }
}
return prime;
}

isPrime(x);//<--no need for "return"

Answer 7

Answer №4

The reason no text appears on the screen is due to the omission of console.log.

Substitute return isPrime(n); with console.log(isPrime(n));.

Answer 8

The reason no text appears on the screen is due to the omission of console.log.

Substitute return isPrime(n); with console.log(isPrime(n));.

Answer 9

Answer №5

Here is the complete code:

    var numbers = ['2', '3', '4', '5', '6', '7']; // Feel free to add more values
    function checkForPrime(num) {
        if (num < 2) {
            return false;
        }
        var isPrime = true;
        for (var i = 2; i <= Math.sqrt(num); i += 1) { 
            if (num % i === 0) {
                isPrime = false;
            }
        }
        return isPrime;
    }
    numbers.forEach(function(value) { 
        console.log('Is ' + value + ' a prime number? ' +  checkForPrime(value)); 
    });
    /*
    // Another way of looping through the array, uncomment this section and comment the one above to see it in action (both will yield the same result)
    for (index = 0; index < numbers.length; ++index) {
        console.log('Is ' + numbers[index] + ' a prime number? ' +  checkForPrime(numbers[index])); 
    }
    */

Answer 10

Here is the complete code:

    var numbers = ['2', '3', '4', '5', '6', '7']; // Feel free to add more values
    function checkForPrime(num) {
        if (num < 2) {
            return false;
        }
        var isPrime = true;
        for (var i = 2; i <= Math.sqrt(num); i += 1) { 
            if (num % i === 0) {
                isPrime = false;
            }
        }
        return isPrime;
    }
    numbers.forEach(function(value) { 
        console.log('Is ' + value + ' a prime number? ' +  checkForPrime(value)); 
    });
    /*
    // Another way of looping through the array, uncomment this section and comment the one above to see it in action (both will yield the same result)
    for (index = 0; index < numbers.length; ++index) {
        console.log('Is ' + numbers[index] + ' a prime number? ' +  checkForPrime(numbers[index])); 
    }
    */

JavaScript Prime Number Checker

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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