用JavaScript正则表达式实现Email验证

     function checkEmail()
   {
    var reg = /\w+[@]\w+[.]\w+/;
    var r = /[@]/;
    var e = /[.]/;
    
    var s_r = 0;
    var s_e = 0;
    var s_rCount = 0;
    var s_eCount = 0;
    
    var str;
    
     str = document.all("test").value;
   
    while(true)
    {
     s_r = str.search(r);
     
     if(s_r != -1)
      s_rCount ++;
     else
      break;
      
     str = str.substring(s_r + 1,str.length);
    }
   
     str = document.all("test").value;
    
    while(true)
    {
     s_e = str.search(e);
     
     if(s_e != -1)
      s_eCount ++;
     else
      break;
      
     str = str.substring(s_e + 1,str.length);
    }
    
     str = document.all("test").value;
    
    var s = str.search(reg);
    
    alert(s);
    alert(s_rCount);
    alert(s_eCount);
    
    if(s == 0 && s_rCount == 1 && s_eCount == 1)
     alert("true");
    else
     alert("false");  
   }