What does the % operator do in JavaScript, and how is it used?

In JavaScript, the `%` operator is called the "remainder" or "modulo" operator. It returns the remainder of the division of one number by another. The syntax is as follows:

result = dividend % divisor;

Here, `dividend` is the number you want to find the remainder of, and `divisor` is the number by which you want to divide.

For example:

let result = 10 % 3;

console.log(result); // Outputs 1, because 10 divided by 3 equals 3 with a remainder of 1

In this example, `10 % 3` returns the remainder of the division of 10 by 3, which is 1.

The `%` operator is often used in programming for various tasks, including:

1. Checking for even or odd numbers:

   - If `num % 2` is 0, then `num` is even; otherwise, it's odd.

   let num = 7;

   if (num % 2 === 0) {

       console.log("Even");

   } else {

       console.log("Odd");

   }

   

2. Cycling through a range of values:

   - By using the modulo operator, you can create a cycling effect within a range of values.

   for (let i = 1; i <= 10; i++) {

       console.log(i % 3); // Outputs 1, 2, 0, 1, 2, 0, 1, 2, 0, 1

   }

   

3. Determine divisibility:

   - You can check if one number is divisible by another using the `%` operator.

   let number = 15;

   if (number % 3 === 0) {

       console.log("Divisible by 3");

   } else {

       console.log("Not divisible by 3");

   }

The `%` operator can be a useful tool in various mathematical and programming scenarios where you need to work with remainders.