With JavaScript off, here is the BM25 side for "search server down", as a local XERJ node scored it: line 2 at 2.079, lines 3 and 5 at 0.9829. The word "down" is in no line, so it adds nothing.
Runs in your browser and sends nothing. The BM25 column uses the formula and defaults in XERJ's bm25.rs (k1 1.2, b 0.75); on these six lines it matched a local XERJ v1.0.0-rc.97 node to 4 decimals for 6 test queries on 2026-10-30. The vector column is a toy: each word gets 5 hand-set numbers (network, server, memory, error, time), not a trained model. Fused score per line is the sum of weight / (k + rank).