function EmailVal(strEmailID) { var strDot="." var AtTheRate="@" var PosAtTheRate=strEmailID.indexOf(AtTheRate) var LenstrEmailID=strEmailID.length var PosStrDot=strEmailID.indexOf(strDot) if (strEmailID.indexOf(AtTheRate)==-1){ alert("Please Enter Valid Email ID..") return false } if (strEmailID.indexOf(AtTheRate)==-1 || strEmailID.indexOf(AtTheRate)==0 || strEmailID.indexOf(AtTheRate)==LenstrEmailID){ alert("Please Enter Valid Email ID..") return false } if (strEmailID.indexOf(strDot)==-1 || strEmailID.indexOf(strDot)==0 || strEmailID.indexOf(strDot)==LenstrEmailID){ alert("Please Enter Valid Email ID..") return false } if (strEmailID.indexOf(AtTheRate,(PosAtTheRate+1))!=-1){ alert("Please Enter Valid Email ID..") return false } if (strEmailID.substrEmailIDing(PosAtTheRate-1,PosAtTheRate)==strDot || strEmailID.substrEmailIDing(PosAtTheRate+1,PosAtTheRate+2)==strDot){ alert("Please Enter Valid Email ID..") return false } if (strEmailID.indexOf(strDot,(PosAtTheRate+2))==-1){ alert("Please Enter Valid Email ID..") return false } if (strEmailID.indexOf(" ")!=-1){ alert("Please Enter Valid Email ID..") return false } return true }</script>
<html><head id="Head1" runat="server"> <title>Untitled Page</title> <script type="text/javascript"> function CheckFormat() { var InputText = document.getElementById('TextBox1').value; var Pattern = /^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*/; if (InputText.search(Pattern)==-1) { alert('Invalid Data'); return false; } } </script></head><body> <form id="form1" runat="server"> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> <asp:Button ID="Button1" runat="server" Text="Button" OnClientClick="return CheckFormat()" /> </form></body></html>