JavaScript substitution function Replace all methods

<script language= "JavaScript" >
var r= "1n2n3n";
Replace the letter N with the component number
Alert (R.replace ("n", ";"));

Result: 1;2n3n only replaced the first
</script>

<script language= "JavaScript" >
var r= "1n2n3n";
Replace the letter N with the component number
Alert (R.replace (/n/g, ";"));

Results: 1;2;3; The first parameter of replace can be a regular expression,/g identity full-text matching.
</script>

<script language= "JavaScript" >
var strm = "JavaScript is a good script language";
Here I want to replace the letter A with the letter A
Alert (Strm.replace ("A", "a"));
</script>

Only the first "a" letter can be replaced

<script language= "JavaScript" >
var strm = "JavaScript is a good script language";
Replace the letter a all with the letter A
Alert (Strm.replace (/a/g, "a"));
</script>

Can replace All "a" letters