JavaScript: Check whether a number is even or not

JavaScript Function: Exercise-7 with Solution

Write a JavaScript program to check whether a number is even or not.

Pictorial Presentation:

Sample Solution-1:

Using recursion:

JavaScript Code:

function is_even_recursion(number)
{
  if (number < 0) 
  {
    number = Math.abs(number);
  }
  if (number===0) 
  {
    return true;
  }
  if (number===1) 
  {
    return false;
  }
  else 
  {
    number = number - 2;
    return is_even_recursion(number);
  }
}
console.log(is_even_recursion(234)); //true
console.log(is_even_recursion(-45)); // false
console.log(is_even_recursion(65)); // false

Output:

true
false
false

Flowchart:

Sample Solution-2:

Without recursion:

Test even number:

• Checks whether a number is odd or even using the modulo (%) operator.
• Returns true if the number is even, false if the number is odd.

Test odd number:

• Check whether a number is odd or even using the modulo (%) operator.
• Return true if the number is odd, false if the number is even.

JavaScript Code:

const is_Even = num => num % 2 === 0;
const is_Odd = num => num % 2 === 1;
console.log("Test even number!")
console.log(is_Even(1));
console.log(is_Even(4));
console.log(is_Even(100));
console.log("Test odd number!")
console.log(is_Odd(1));
console.log(is_Odd(4));
console.log(is_Odd(107));

Output:

Test even number!
false
true
true
Test odd number!
true
false
true

Live Demo:

See the Pen javascript-recursion-function-exercise-7 by w3resource (@w3resource) on CodePen.

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