Find the smallest and largest value in an array with JavaScript

Question

I am trying to write an algorithm that finds and smallest and largest value in an array, and the second largest and second smallest.

I tried with the following:

numbers = [2, 4, 9, 2, 0, 16, 24]

var largest = numbers[0];
var smallest = numbers[0];

for (var i = 1; i < numbers.length; i++) {

  if (numbers[i] > largest) {
    largest = numbers[i];
  } else if (numbers[i] < smallest) {
    smallest = numbers[i];
  }

  console.log(largest);
  console.log(smallest);
}

This does not seem to work and just prints out the array...what am I doing wrong?

Answer 1

The easiest way to do this would be to sort the array, then return the first two and last two elements.

Using slice() prevents the array itself from being sorted:

var numbers = [2, 4, 9, 2, 0, 16, 24];

var sorted = numbers.slice().sort(function(a, b) {
  return a - b;
});

var smallest = sorted[0],                      
    secondSmallest = sorted[1],                
    secondLargest = sorted[sorted.length - 2], 
    largest  = sorted[sorted.length - 1];

console.log('Smallest: ' + smallest);
console.log('Second Smallest: ' + secondSmallest);
console.log('Second Largest: ' + secondLargest);
console.log('Largest: ' + largest);

Answer 2

Move your console.log statements outside of your for loop.