javascript 中的replace方法

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.

replace()
The replace() method returns the string that results when you replace text matching its first argument
   (a regular expression) with the text of the second argument (a string).
   If the g (global) flag is not set in the regular expression declaration, this method replaces only the first
    occurrence of the pattern. For example,

var s = "Hello. Regexps are fun.";s = s.replace(/\./, "!"); // replace first period with an exclamation pointalert(s);

produces the string “Hello! Regexps are fun.” Including the g flag will cause the interpreter to
    perform a global replace, finding and replacing every matching substring. For example,

var s = "Hello. Regexps are fun.";s = s.replace(/\./g, "!"); // replace all periods with exclamation pointsalert(s);

yields this result: “Hello! Regexps are fun!”