JavaScript: How to check if a number is even without using the modulo operator?

Javascript Web Development Front End Technology

Often we need to check whether a number is odd or even and return the same to the user. In this article also we will be checking whether a number is even or not but without using the modulo operator. It’s pretty easy to check whether a number is even by using the modulo operator. But we can also check a number with other possible methods.

Below we are going to see the other methods for checking a number and its properties.

Approach #1: Using the for() loop

In this method, we are going to use the for() loop to check whether a number is even or not. The idea is to take a Boolean flag variable as true and check it up to n times. If the flag gets its value back it means the value was even else not.

Example 1

In the below example, we are going to check whether a number is even or not by using the for() loop approach.

# index.html

<!DOCTYPE html>
<html>
<head>
   <title>Checking If a Number is Even</title>
</head>
<body>
   <h1 style="color: green">
      Welcome To Tutorials Point
   </h1>
   <script>
      // Returns true if n is even,
      function isEven(n) {
         let isEven = true;
         for(let i = 1; i <= n; i++)
            isEven = !isEven;
         if (isEven)
            console.log(n + " is an Even number.");
         else
            console.log(n + " is Odd.");
      }
      // Driver Code
      isEven(101);
      isEven(158);
   </script>
</body>
</html>

Output

The above program will produce the result in the console similar to the below screenshot −

Approach #2: Using multiplication and division

In this method, we are going to divide a number by 2 and then multiply the result by 2. If the result is the same as that of the original number, it is an even number.

Example 2

In the below example, we are going to check whether a number is even or not by using multiplication and division.

# index.html

<!DOCTYPE html>
<html>
<head>
   <title>Checking If a Number is Even</title>
</head>
<body>
   <h1 style="color: green;">
      Welcome To Tutorials Point
   </h1>
   <script>
      // Returns true if n is even,
      function isEven(n) {
         // Return true if n/2 does not result
         // in a float value.
         if(parseInt(n / 2, 10) * 2 == n) {
            console.log(n + " is an Even number.");
         } else {
            console.log(n + " is Odd.");
         }
      }
      // Driver Code
      isEven(101);
      isEven(158);
   </script>
</body>
</html>

Output

The above program will produce the result in the console similar to the below screenshot −

Approach #3: Using the bitwise operator

In this method, we are going to use the bitwise AND operator to check the number.

Example #3

# index.html

<!DOCTYPE html>
<html>
<head>
   <title>Checking If a Number is Even</title>
</head>
<body>
   <h1 style="color: green;">
      Welcome To Tutorials Point
   </h1>
   <script>
      // Returns true if n is even,
      function isEven(n) {
         // n&1 is 1, then odd, else even
         if (!(n & 1)) {
            console.log(n + " is an Even number.");
         } else {
            console.log(n + " is Odd.");
         }
      }
      // Driver Code
      isEven(101);
      isEven(158);
   </script>
</body>
</html>