How can I check, if anyone entered a special character, in the signup form? : phpMyAnswers

How can I check, if anyone entered a special character, in the signup form?

demo 20 Dec 2008 05:59am
I dont want users to enter special letters as their usernames, in the signup form.

how can I check it in ASP? (or javascript)
only accepted letters must be A to Z, a to z and numbers only.
if someone enter a letter which is not in english alphabet it must raise an error.
i have enough knowledge about asp or javascript. i will be happy if you write the function only. i understand it. thanks.

Answers

demo 20 Dec 2008 07:27am
I wrapped the solution in "just enough" HTML for a demo.

<head>
<style>
</style>
<script type="text/javascript">
function validate( bRef ) {
// get field to be validated
var fld = document.getElementById( 'field0' ).value;
// use regular expression pattern matching to detect
// any characters NOT in the composite character set,
// consisting of upper and lower case alphabetics and
// numeric digits
var invalid = fld.match( /[^A-Z,a-z,0-9]/g );
// if no matches, then all were valid, and content
// of {invalid} is {null} (NOTE: ^ negates the set)
if (null == invalid) {
// do whatever you want for valid input, e.g.,
// var f = document.getElementById( 'myForm' );
// OR var f = bRef.parentNode;
// f.submit();
}
else {
// do whatever you want for invalid input, e.g.,
alert('form contains invalid characters:n' + invalid);
}
}
</script>
</head>
<body>
For demo purposes...
<form id="myForm">
<input type="text" id="field0" />
<input type="button" value="submit" onclick="validate( this )" />
</form>
</body>
</html>

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