wouldn't that return the value of currentChunk before it was incremented? So it would need an additional line to be equivalent to the example (making it a bit more readable in my opinion):
currentChunk++;
this.chunks[currentChunk] = [];
Which is perhaps what you meant all along. Please excuse the pedantry.
Yeah, that's what I meant - instead of taking the shortcut with a comment explaining it, just don't take it in the first place.