JavaScript: Even, odd numbers and their sum in an array

JavaScript Math: Exercise-94 with Solution

Sum and Count of Even and Odd Numbers

Write a JavaScript program to calculate the sum and count of even and odd numbers in an array.

Test Data:
([1,2,3,4,5,6,7]) -> 3,12, 4,16
([2,3,5,1,2,0,3,4,2,3,4)] -> 6,14, 5,15

Sample Solution:

JavaScript Code:

/**
 * Function to count the number of even and odd numbers and their sums in an array.
 * @param {number[]} nums - The array of numbers to be processed.
 * @returns {number[]} - An array containing the count and sum of even and odd numbers, respectively.
 */
function test(nums) {
  let even = 0, odd = 0;
  nums.forEach(number => {
    if (number % 2 === 0) 
      even++;
    else
      odd++;
  });
  return [
    even,
    nums.reduce((s, v) => (!(v % 2) ? s + v : s), 0),
    odd,
    nums.reduce((s, v) => (v % 2 ? s + v : s), 0)
  ];
}

// Test cases
let nums = [1, 2, 3, 4, 5, 6, 7];
console.log("Original array: " + nums);
let result = test(nums);
console.log("Number of even numbers and their sum: " + result[0] + "," + result[1]);
console.log("Number of odd numbers and their sum: " + result[2] + "," + result[3]);

nums = [2, 3, 5, 1, 2, 0, 3, 4, 2, 3, 4];
console.log("Original array: " + nums);
result = test(nums);
console.log("Number of even numbers and their sum: " + result[0] + "," + result[1]);
console.log("Number of odd numbers and their sum: " + result[2] + "," + result[3]);

Output:

Original array: 1,2,3,4,5,6,7
Number of even numbers and their sum: 3,12
Number of odd numbers and their sum: 4,16
Original array: 2,3,5,1,2,0,3,4,2,3,4
Number of even numbers and their sum: 6,14
Number of odd numbers and their sum: 5,15

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-94 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that iterates through an array and separately calculates the sum and count of even numbers.
• Write a JavaScript function that uses the reduce() method to compute the sum and count of odd numbers in an array.
• Write a JavaScript function that returns an object with properties evenCount, evenSum, oddCount, and oddSum after processing an array.
• Write a JavaScript function that validates the input array and handles cases where one type (even/odd) is absent.

Go to:

• JavaScript Math and Numbers Exercises Home ↩
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