“Stretch out...so Joshua stretched out.” Here again in Joshua 8:18 we see the emphasis on Joshua’s quick and exact obedience to God, which has been a theme in Joshua (see commentary on Josh. 4:16).
“javelin.” The exact weapon the Hebrew word refers to is debated. It is traditionally a spear, but it could also be a short, curved sword. That seems to be the use in the Qumran material and short curved swords have been found by archaeologists from Joshua’s time, but there is also a long time between the time of Joshua and the Qumran writing, so the word is debated.