because of best practices

Not an issue, your code was wrong, but you got lucky and passed it.

You could have more than the exact amount of fuel needed to get to the pump.

Please don't put issues on katas if you don't even know what it means.

The tests only work if the test before it works. For example test 2 is called in and is applied if test 1 is passed. Therefore, issue is resolved.

Read what kind of input those methods have.

You can't compare arrays like this.

I thought that const meant that the variable is a constant so it can't be changed

Reading documentation > assuming how something works.

Because Array.prototype.sort works in-place.