validation code in javascript for email validation

<script>
function validateForm()
{
var x=document.forms["register"]["email"].value;
var atpos=x.indexOf("@");
var space=x.indexOf(" ");
var dollar=x.indexOf("$");
var hash=x.indexOf("#");
var per=x.indexOf("%");
var or=x.indexOf("^");
var amber=x.indexOf("&");
var star=x.indexOf("*");
var plus=x.indexOf("+");
var minus=x.indexOf("-");
var coma=x.indexOf(",");
var dotpos=x.lastIndexOf(".");
var neg=x.indexOf("~");
var neq=x.indexOf("!");
var b1=x.indexOf(")");
var b2=x.indexOf("(");
var b3=x.indexOf(":");
var b5=x.indexOf("?");
var b6=x.indexOf(">");
var b7=x.indexOf("<");
var b8=x.indexOf("}");
var b9=x.indexOf("{");
var b10=x.indexOf("|");
if (x==null || x=="")
  {
  alert("Email is mandatory");
  return false;
  }
 
 if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length || space>0 || dollar>0 || hash>0 || per>0 || or>0 || amber>0 || star>0 || plus>0 || minus>0 || coma>0 || neg>0 || neq>0 || b1>0 || b2>0 || b3>0 || b5>0 || b6>0 || b7>0 || b8>0 || b9>0 || b10>0)
  {
  alert("Not a valid e-mail address");
  return false;
  }
  }
  </script>
<form name="register" onsubmit="return validateForm()" action='http:\\www.google.com' method='get'>
<font face="Times New Roaman">Email Address*</font></td><td><input type='text' name='email' value='example@domain.com' onblur="if (this.value == '') {this.value = 'example@domain.com';}"
 onfocus="if (this.value == 'example@domain.com') {this.value = '';}">
 <input type='submit' value='submit'>
</form>