Code: <html><head> <script language = "Javascript"> function echeck(str) { var at="@" var dot="." var lat=str.indexOf(at) var lstr=str.length var ldot=str.indexOf(dot) if (str.indexOf(at)==-1) { alert("Invalid E-mail ID") return false } if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr) { alert("Invalid E-mail ID") return false } if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr) { alert("Invalid E-mail ID") return false } if (str.indexOf(at,(lat+1))!=-1) { alert("Invalid E-mail ID") return false } if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot) { alert("Invalid E-mail ID") return false } if (str.indexOf(dot,(lat+2))==-1) { alert("Invalid E-mail ID") return false } if (str.indexOf(" ")!=-1) { alert("Invalid E-mail ID") return false } return true } function ValidateForm(){ var emailID=document.frmSample.txtEmail if ((emailID.value==null)||(emailID.value=="")){ alert("Please Enter your Email ID") emailID.focus() return false } if (echeck(emailID.value)==false){ emailID.value="" emailID.focus() return false } return true } </script> </head> <body> <form name="frmSample" method="post" action="#" onSubmit="return ValidateForm()"> <p>Enter an Email Address : <input type="text" name="txtEmail"> </p> <p> <input type="submit" name="Submit" value="Submit"> </p> </form> </body> </html>
