Came up with a short basic solution:
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;
}