UNDOCUMENTED MECHANICS
The bolts reach 20 yards.
The "N attacks" the game shows is 2 + (level − 1), and the table labels it "# of target jump hits" — that is how many targets the arc can chain through, not how many times it hits one monster.
The missile table is explicit: CollideKill = 1, so the arc is destroyed on impact, and its hit function then looks for another target within range to spawn a fresh arc. So with nothing else nearby to act as a node the chain simply ends — the remaining jumps are wasted.
That is the division of labour with Charged Strike: this one clears packs, while Charged Strike is the better single-target choice.
The javelin's own physical weapon damage is resolved separately from the lightning damage above.