checkEven()

Step 1: Define the Function

The first step is to define the function. In JavaScript, you can define a function using the function keyword followed by the function's name. In this case, let's name the function checkEven. This function will take one parameter which is the number that we need to check whether it is even or not. In this step, we will just declare the function, we will not write its full logic yet.

function checkEven(num) {
  // code comes here
}

Step 2: Implement the If Statement

Inside this function, we will use an if statement to check if the number is even. In JavaScript, a number is even if it is divisible by 2 with no remainder. We can use the modulus % operator for this purpose. If a number is even, the modulus of that number and 2 equals 0 (num % 2 === 0).

function checkEven(num) {
  if (num % 2 === 0) {
    // code comes here
  }
}

Step 3: Implement the Return Statement for Even Number

When the number is even, we need to return the true value from the function to indicate that the input number is even. We can do this using the return statement in JavaScript.

function checkEven(num) {
  if (num % 2 === 0) {
    return true;
  }
}

Step 4: Implement the Return Statement for Odd Number

For the case when the number is not even (i.e., the number is odd), we need to return false. We can simply add a return false; statement after the if statement from step 2. When the if condition fails (which means the number is not even), JavaScript will execute this return false; line.

function checkEven(num) {
  if (num % 2 === 0) {
    return true;
  }
  return false;
}

Step 5: Testing the checkEven function

It is always a good idea to test your functions to ensure that they work as expected. Let's test our checkEven function with some sample numbers.

console.log(checkEven(2)); // should print true
console.log(checkEven(7)); // should print false

Conclusion:

Here is the full code of our checkEven function. This function takes one number as input and returns true if the number is even and false if the number is odd.

function checkEven(num) {
  if (num % 2 === 0) {
    return true;
  }
  return false;
}
console.log(checkEven(2)); // true
console.log(checkEven(7)); // false

This completes the implementation of our checkEven function. Using this function, you can now easily check if any number is even or odd in JavaScript.