Can anyone explain this code? Smallest Common Multiple

JavaScript
1

Tell us what’s happening:

Your code so far


function smallestCommons(arr) {

  let newArr = [];
  arr.sort((a,b)=>a-b);
  for (let i = arr[0] ; i<arr[1] ; i++){
    newArr.push(i);
  }
  
  
   return arr;
}


smallestCommons([1,5]);

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.87 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/smallest-common-multiple

I am only able to do this far at the moment.
I’ve stuck here for a while.
I’ve checked the math algorithm of the least common multiple.
I want to read some codes to help me understand better and I came across this code

function smallestCommons(arr) {

  var max = Math.max(arr[0], arr[1]);
  var min = Math.min(arr[0], arr[1]);
  var mltple = max;

  for(var i = max; i >= min; i--){
    if(mltple % i !== 0){
     mltple += max; 
      i = max;
    } 
  }

  return mltple;  
}

smallestCommons([1,5]);   //

I don’t understand the logic of this code…
I tried to put a number inside, but am still confused.

For the first round of for loop, is

 for(var i = max; i >= min; i--){
       // i=5 ; i>=1 ; i--
    if(mltple % i !== 0){
   //if (5 % 5 !== 0){
// here 5 % 5 == 0 so the rest code will not excute. 
     mltple += max; 
      i = max;

    } 
  }

then the second round is

 for(var i = max; i >= min; i--){
 // for(i = 5; i>=1 ; i--){
    if(mltple % i !== 0){
   //if (5 % 4 !==0){
     mltple += max;      //mltple = 5+5 
 
      i = max;  //   i = 5?;
    } 
  }

then third round became

for(i = 5 ; i>=1 ; i--){
if (5% 3 !==0){
mltple += max;  // mltple = 10+5
i = max; //  i = 5;


for(i = 5 ; i>=1 ; i--){
if (5% 2 !==0){
mltple += max;  // mltple = 15+5
i = max; //  i = 5;

for(i = 5 ; i>=1 ; i--){
if (5% 1 !==0){
//5 % 1 == 0, so the code won't excute the line below and for loop is also finished. (because i = 1 now)
mltple += max;  
i = max; //  i = 5;

But then the value of return mltple; is only 20.
Did I make any terrible mistake here???