My solution to this problem is this:

```
function smallestCommons(arr) {
let start = Math.min(...arr);
let end = Math.max(...arr);
let number = end;
let stop = false;
console.log("start", start, "end", end, "number", number);
while(!stop){
let valid = true;
for(let i=start; valid && (i <= end); i++){
valid = (number % i === 0);
}
if(valid)
stop = true;
else
number++;
}
console.log("Arr", arr, "Number:", number);
return number;
}
```

I tried out directly in the browser and it is working correctly but when I run on FCC it fails for [1, 13] and [23,18].