replace函数疑问

Question

<SCRIPT LANGUAGE="JavaScript">
<!--
c = "g";
a = "abcdefg";
b = eval("a.replace(/"+c+"/gi,'x')");
alert(b);
//-->
</SCRIPT>

Answer 1

改成是这样
<SCRIPT LANGUAGE="JavaScript">
<!--
c = "g";
a = "abcdefg";
re = new RegExp(c,"gi")
b = a.replace(re,"x");
alert(b);
//-->
</SCRIPT>

Answer 2

这样就OK 了,呵呵!
<SCRIPT LANGUAGE="JavaScript">
<!--
c = "g";
a = "abcdefg";
var myString="a.replace(/"+c+"/gi,'x')";
var result=eval(myString);
alert(result);
//-->
</SCRIPT>