How to determine if a number is odd in JavaScript

Question

Can anyone point me to some code to determine if a number in JavaScript is even or odd?

Answer 1

Use the bitwise AND operator.

function oddOrEven(x) {
  return ( x & 1 ) ? "odd" : "even";
}

function checkNumber(argNumber) {
  document.getElementById("result").innerHTML = "Number " + argNumber + " is " + oddOrEven(argNumber);
}
 
checkNumber(17);

If you don't want a string return value, but rather a boolean one, use this:

var isOdd = function(x) { return x & 1; };
var isEven  = function(x) { return !( x & 1 ); };