I’m trying to solve this problem in an inefficient but easy to understand way: store the prime factors of all numbers in the range as objects eg for 12 = 2^2 * 3 :

`{ 2: 2, 3: 1 }`

Then form the answer as the product of these prime factors raised to the highest power needed to form any individual number in the range. eg if the ‘range’ - not contiguous here for illustrative purposes - included just 8, 9 in addition to 12 :

`{ 2: 3 }`

`{ 3: 2 }`

The answer is:

`{ 2: 3, 3: 2 }`

= 72

Console logging is showing me that lcmf object - which I want to watch building up these factors - is fully populated even though it was just declared in the previous line, eg

`var lcmf = {};`

I tried running the code directly in the browser with the same result. This is is making debugging impossible & me very confused - so thanks for having a look.

Here’s the code:

```
function testPrime(primes, p) {
return primes.every(function(el){
//console.log(p, el, p%el, p%el==0);
return p%el != 0;
}
);
}
function listPrimes(mx) {
var res = [];
var primes = [2];
for (var i=2; i<=mx; i++){
if (testPrime(primes, i)) {
primes.push(i);
}
}
return primes;
}
function primeFac(primes, p){
PFO = { }; // prime factor object
var n = 0;
for (var i=primes.length-1; i>=0; i--) {
while (p%primes[i]==0){
n += 1;
p /= primes[i];
}
if (n>0) {
PFO[primes[i]] = n;
}
n = 0;
}
//console.log(PFO);
return PFO;
}
function smallestCommons(arr) {
var l = Math.max(arr[0], arr[1]);
var s = Math.min(arr[0], arr[1]);
var lcmf = {}; // LCM factor object
console.log("lcmf>>", lcmf);
var PFOs = [];
var primes = listPrimes(l);
console.log(l, s, "primes:", primes, lcmf, PFOs, "...");
for (i=l; i>=s; i--){
PFOs.push(primeFac(primes,i));
}
console.log("<", lcmf);
for (i=0; i<PFOs.length; i++){
console.log(i, lcmf, PFOs[i]);
for (var k in PFOs[i]) {
if (lcmf.hasOwnProperty(k)){
lcmf[k] = Math.max(PFOs[i][k], lcmf[k]);
} else {
lcmf[k] = PFOs[i][k];
}
}
console.log("->", lcmf);
}
console.log("--------------------------------------");
return 1; // need to take product of powered factors
}
smallestCommons([1, 13]);
```