Discussion on: If/else or just if?

I think the second example is muddying the water by combining the pattern (failing early) with a style choice (single-line, braceless ifs).

I prefer Statement B, or would if it was written like this:

if (typeof val === 'string') {
  return 'A';
}

if (val === null || val === undefined) {
  return 'B';
}

return val;

I like this because it reduces nesting and acts as a barrier to people over-complicating a function. I mean that if the function ends up having to re-use a negated form of one of the earlier conditions or have a separate set of nested ifs after the guard conditions, then it's a big smelly smell and should be moved to its own function instead.

Also, if you think about it in terms of human experience, it's how we work. If you're tending a patch of garden, you don't think about what category of flower you're looking at and cross-reference it in a book if it's obviously a weed.