以下代码中，我有一个地方不大明白，希望能得到大家的帮助，给我解释以下，谢谢了。

Function CheckStr(str)
'函数作用:过滤危险字符
str = Replace(str,"javascript","ｊavascript")
str = Replace(str,"!","")
str = Replace(str,"]","")
str = Replace(str,"[","")
str = Replace(str,")","")
str = Replace(str,"(","")
str = Replace(str,"　","")
str = Replace(str,"/","")
str = Replace(str,"+","")
str = Replace(str,"=","")
str = Replace(str,",","")
str = Replace(str,"'","")
CheckStr = str
End Function

在这段代码中，”CheckStr = str“，起到了个什么作用，具体是什么意思，希望大家能给我讲解下，谢谢了。