而str.replace(/-/g,"!")则可以替换掉全部匹配的字符（g为全局标志）。
replace()
Thereplace()methodreturnsthestringthatresultswhenyoureplacetextmatchingitsfirstargument
(aregularexpression)withthetextofthesecondargument(astring).
Iftheg(global)flagisnotsetintheregularexpressiondeclaration,thismethodreplacesonlythefirst
occurrenceofthepattern.Forexample,
vars="Hello.Regexpsarefun.";s=s.replace(/./,"!");//replacefirstperiodwithanexclamationpointalert(s);
producesthestring“Hello!Regexpsarefun.”Includingthegflagwillcausetheinterpreterto
performaglobalreplace,findingandreplacingeverymatchingsubstring.Forexample,
vars="Hello.Regexpsarefun.";s=s.replace(/./g,"!");//replaceallperiodswithexclamationpointsalert(s);
yieldsthisresult:“Hello!Regexpsarefun!”
