▁HTML , ▁DOM , ▁X HR , ▁and ▁JavaScript . ▁ ▁Fire bug ▁was ▁lic ensed ▁under ▁the ▁B SD ▁license ▁and ▁was ▁initially ▁written ▁in ▁January ▁ 2 0 0 6 ▁by ▁Joe ▁H ew itt , ▁one ▁of ▁the ▁original ▁Firefox ▁cre ators . ▁The ▁Fire bug ▁Working ▁Group ▁o vers aw ▁the ▁open ▁source ▁development ▁and ▁extension ▁of ▁Fire bug . ▁It ▁had ▁two ▁major ▁implementations : ▁an ▁extension ▁for ▁Moz illa ▁Firefox ▁and ▁a ▁book mark let ▁implementation ▁called ▁Fire bug ▁L ite ▁which ▁can ▁be ▁used ▁with ▁Google ▁Chrome . ▁ ▁In ▁addition ▁to ▁debugging ▁web ▁pages , ▁Fire bug ▁was ▁used ▁for ▁web ▁security ▁testing ▁and ▁web ▁page ▁performance ▁analysis . ▁ ▁Fire bug ▁has ▁been ▁deprecated ▁in ▁favor ▁of ▁the ▁integrated ▁developer ▁tools ▁added ▁to ▁Firefox ▁itself , ▁whose ▁functionality ▁has ▁been ▁un ified ▁with ▁those ▁of ▁Fire bug . ▁As ▁Firefox ▁ 5 7 ▁no ▁longer ▁supports ▁X UL ▁add - ons , ▁Fire bug ▁is ▁no ▁longer ▁compatible . ▁ ▁Version ▁history ▁ ▁Version ▁ 2 . 0 ▁ ▁Fire bug ▁ 2 . 0 ▁introduced ▁many ▁new ▁features ▁to ▁the ▁Fire bug ▁extension ▁including ▁JavaScript ▁syntax ▁highlight ing , ▁pretty ▁print ▁for ▁min ified ▁JavaScript ▁code , ▁and ▁a ▁DOM ▁Event ▁Ins pect or ▁to ▁handle ▁all ▁event ▁handlers ▁on ▁a ▁web ▁page . ▁Additionally , ▁users ▁can ▁search ▁for ▁page ▁elements ▁using ▁CSS ▁select ors ▁in ▁the ▁search ▁bar . ▁The ▁debugging ▁tool ▁now ▁allows ▁users ▁to ▁inspect ▁JavaScript ▁expressions ▁as ▁they