Generating code from the decision tree can result in this kind of structure on the JS target:

if (cond) {
  // ...
} else {
  if (other_cond) {
    // ...
  } else {
    // ...
  }
}

It would be a nice touch if the generated code looked like this instead:

if (cond) {
  // ...
} else if (other_cond) {
  // ...
} else {
  // ...
}

This is not as straightforward as it seems since sometimes we might have variable definitions in between an else and the nested if, making it impossible to collapse into an else if.