Description of replace method in JavaScript_javascript skills

For the first time, I discovered that the replace() method in JavaScript will only replace the first matching character if str.replace("-","!") is used directly.
And str.replace(/-/g,"!") can replace all matching characters (g is a global flag).​

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 replacement, 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!”