Entry
How can I check an email address for valid domain and format?
Apr 7th, 2008 22:45
ha mo, Abolfazl Shirazi, Jim Owen, Abolfazl Shirazi
Abolfazl Shirazi
The answer of this question is quite easy . You can't
check an email address to see whether it is valid or
not . Because the user of your site can type every
things . BUT you can easily check that email address
for valid format and correct characters . for example
having @ symbol or not having bad characters or ....
The script below check email addresses for valid and
correct formats :
<html>
<head>
<script language="javascript" type="text/javascript">
function checkform() {
text=document.myform.textfield.value
// The Field Shouldn't be Empty
if (text == "") {
alert("Please Enter Your Email Address To Check .")
return false
}
// Check For Bad Chars
badchar = " ()<>\/[]{}+-*|;,'"
for (i=0;i<text.length;i++) {
for (j=0;j<badchar.length;j++) {
if (text.charAt(i) == badchar.charAt(j)) {
alert("Your Email Address May Has Some
Bad Character or there is some space between letters")
return false
}
}
}
// There Should Be a dot (.) Symbol
if (text.indexOf(".") == -1) {
alert("Your Email Address Doesnot have any dot(.)
symbol")
return false
}
// There Should Be an @ Symbol
if (text.indexOf("@") == -1) {
alert("Your Email Address Doesnot have any @ symbol")
return false
}
else {
// Only one @ symbol should be found
symbolfound = 0
for (i=0;i<text.length;i++) {
if (text.charAt(i) == "@") {
symbolfound++
}
else {
continue
}
}
if (symbolfound != 1) {
alert("Ooops Your Email Address Has More Than
One @ Symbol")
return false
}
}
// Check For Syntax Errors Such as .@ or @. or ..
if (text.indexOf("@.") != -1 || text.indexOf(".@") != -1 ||
text.indexOf("..") != -1) {
alert("Sorry Your Email Address has two symbol side by
side and it is wrong")
return false
}
// The first character shouldn't be @ or .
if (text.charAt(0) == "@" || text.charAt(0) == ".") {
alert("OH your first character seem to be . or @ and it
is wrong")
return false
}
// The last character shouldn't be @ or .
if (text.charAt(text.length-1) == "@" || text.charAt
(text.length-1) == ".") {
alert("OH your last character seem to be . or @ and it
is wrong")
return false
}
// The @ Symbol should be found before .
foundchar1 = text.indexOf("@")
foundchar2 = text.indexOf(".")
if (foundchar1 > foundchar2) {
alert("Sorry The @ Symbol should be found before dot(.)
symbol but it isnt in yours")
return false
}
alert("Perfect ! "+ text + " is a valid Email Address .")
return false
}
</script>
</head>
<body>
<h1>Enter Your E-mail Address</h1>
<form name="myform" onsubmit="return checkform()">
<input type="text" name="textfield">
<p>
<input type="submit" name="submitbutton" value="Check">
<input type="reset" name="resetbutton" value="Reset"><p>
</form>
</body>
</html>
Enjoy It !!!
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