Descending for loop in solution for Smallest Common Multiple challenge

JavaScript
1

I don’t understand the for loop in the basic code solution for this challenge.

I don’t get what’s going on in for (var i = arr[0]; i >= arr[1]; i--) at all (though I understand the push method).

This is the full solution:

function smallestCommons(arr) {
  // Sort array from greater to lowest
  // This line of code was from Adam Doyle (http://github.com/Adoyle2014)
  arr.sort(function(a, b) {
    return b - a;
  });

  // Create new array and add all values from greater to smaller from the
  // original array.
  var newArr = [];
  for (var i = arr[0]; i >= arr[1]; i--) {
    newArr.push(i);
  }

  // Variables needed declared outside the loops.
  var quot = 0;
  var loop = 1;
  var n;

  // Run code while n is not the same as the array length.
  do {
    quot = newArr[0] * loop * newArr[1];
    for (n = 2; n < newArr.length; n++) {
      if (quot % newArr[n] !== 0) {
        break;
      }
    }

    loop++;
  } while (n !== newArr.length);

  return quot;
}

// test here
smallestCommons([1,5]);
2

You have a sorted array of 2 items. You start with the first item (arr[0]), and decrement until you hit the second item (arr[1]), pushing every number between arr[0] and arr[1] into the new array.

So, using the example, the loop becomes:

for (i = 5; i >= 1; i--) {
  newArr.push(i); // (push 5, push 4, push 3, push 2, push 1)
}
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