My first doubts is: Am I collecting the numbers from the array correctly?

Some aid would be greatly appreciated.

```
// function sumAll(arr) {
let firstN = arr[0];
let secondN = arr[1];
let a = 0;
if(firstN <= secondN) {
for(firstN; firstN <= secondN; firstN++) {
return a += firstN
}//for
} else if (firstN >= secondN) {
for(firstN; firstN >= secondN; firstN--) {
return a += firstN
}
}
}
sumAll([1, 4]);
```