Find if variable is divisible by 2

Question

Use modulus:

// Will evaluate to true if the variable is divisible by 2
variable % 2 === 0  

Seriously, there's no jQuery plugin for odd/even checks?

Well, not anymore - releasing "Oven" a jQuery plugin under the MIT license to test if a given number is Odd/Even.

Source code is also available at http://jsfiddle.net/7HQNG/

Test-suites are available at http://jsfiddle.net/zeuRV/

(function() {
    /*
     * isEven(n)
     * @args number n
     * @return boolean returns whether the given number is even
     */
    jQuery.isEven = function(number) {
        return number % 2 == 0;
    };

    /* isOdd(n)
     * @args number n
     * @return boolean returns whether the given number is odd
     */
    jQuery.isOdd = function(number) {
        return !jQuery.isEven(number);
    };
})();​

You don't need jQuery. Just use JavaScript's Modulo operator.

You can do it in a better way (up to 50 % faster than modulo operator):

odd: x & 1 even: !(x & 1)

Reference: High Performance JavaScript, 8. ->Bitwise Operators

You can use the modulus operator like this, no need for jQuery. Just replace the alerts with your code.

var x = 2;
if (x % 2 == 0)
{
  alert('even');
}
else
{
  alert('odd')
}

You can also:

if (x & 1)
 itsOdd();
else
 itsEven();

if (x & 1)
 itIsOddNumber();
else
 itIsEvenNumber();