字符串判断的问题

Question

<SCRIPT LANGUAGE="JavaScript">
function isEmail(str)
{
  return new RegExp(/^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/).test(str);
}alert(isEmail("[email protected]"));
alert(isEmail("aaa@bbb@ccc"));
alert(isEmail("aaa.bbb.ccc"));
</SCRIPT>

Answer 1

<SCRIPT LANGUAGE="JavaScript">
function strEmail(str){
var pattern = /^([\.a-zA-Z0-9_-]){2,}@([a-zA-Z0-9_-]){2,}(\.([a-zA-Z0-9]){2,4}){1,2}$/; 
return pattern.test(str);
}
alert(strEmail("[email protected]"));
alert(strEmail("aaa@bbb@ccc"));
alert(strEmail("aaa.bbb.ccc"));
</SCRIPT>