Don't know why I am getting an alert! 'undefined' message
Question
I am learning PHP, JavaScript. The code that follows comes from a textbook that I am using.
<script>
function validate(form)
{
fail = validateForename(form.forename.value)
fail += validateSurname(form.surname.value)
fail += validateUsername(form.username.value)
fail += validatePassword(form.password.value)
fail += validateAge(form.age.value)
fail += validateEmail(form.email.value)
if (fail == "") return true
else { alert(fail); return false }
}
<body>
<table border="0" cellpadding="2" cellspacing="5" bgcolor="#eeeeee">
<th colspan="2" align="center">Signup Form</th>
<form method="post" action="adduser387.php" onSubmit="return validate(this)">
<tr><td>Forename</td> ....
The validate functions work. When all fields are validated and I 'submit', the logic falls through to 'else { alert(fail); return false }' giving me an 'undefined' message - not sure why. Please let me know if I provided insufficient info. I could not find an answer on the Internet. Thanks.
1 answers
solution1
0 2015-09-27 05:04:31
Your js function has to be like this:
function validate(form) {
var fail = '';
fail += validateForename(form.forename.value);
fail += validateSurname(form.surname.value);
fail += validateUsername(form.username.value);
fail += validatePassword(form.password.value);
fail += validateAge(form.age.value);
fail += validateEmail(form.email.value);
if (fail == "") {
return true;
}
else {
alert(fail);
return false
}
}
Problem with your script is
failis not defined anywhere hence its value isundefined(not considering your filed validation functions return value), hence value iffail == ""will never betrueasundefinedis not equals to''and thats why your else condition is getting satisfied. As there isundefinedvalue infail, you are getting alert asundefined
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