第一次发现JavaScript中replace()方法如果直接用str.replace("-","!")只会替换第一个匹配的字符.

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!”