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javascript validation with regular expression not working

In my asp.net web application. I need to validate a textbox entry to avoid these special characters \/:*>"<>|.I planned to replace the character with empty string, and for that wrote a javascript function and addded the attribute to call the function from server side as below
txtProjectName.Attributes.Add("onkeyup", "ValiateSpecialCharacter()");
As of this every thing is fine and the function is called.while enter any character. The function is
function ValiateSpecialCharacter(){
var txt=document.getElementById("<%=txtProjectName.ClientID%>").value;
txt.replace(/[\\\/:*>"<>|]/g, '');
alert(txt);
document.getElementById("<%=txtProjectName.ClientID%>").value=txt;
}
I use a regular expression in the function to do this. But the test is not getting replaced as planned. Is there any mistake in this code.Also note that the alert is working.

Try to get the result in txt ie, get the value of replaced text inside your variable.
txt = txt.replace(/[\\\/:*>"<>|]/g, '');

In your query you getting previous value.Assign properly like this txt = txt.replace(/[\\\/:*>"<>|]/g, '');.It show the latest result in alert box.
function ValiateSpecialCharacter(){
var txt=document.getElementById("<%=txtProjectName.ClientID%>").value;
txt = txt.replace(/[\\\/:*>"<>|]/g, '');
alert(txt);
document.getElementById("<%=txtProjectName.ClientID%>").value=txt;
}

This is not what you asked, but seems like a strange way to go about your needs. Unless, I misunderstood the question. Since you are running ASP.NET on the server, why use JavaScript for server validation?
It usually does make sense to validate input on the client. For that, you need to hook an event like form submit to call the javascript function.
If you want to validate on the server, use something like, inside a function handling form submit:
Regex re = new Regex("^[a-zA-Z0-9][a-zA-Z0-9-]{1,61}[a-zA-Z0-9](?:\\.[a-zA-Z]{1,})+$");
if (!re.IsMatch (domain.Text)) {
warningLabel.Text = "Domain format is invalid!";
formError = true;
}
Obviously, you don't validate the domain so change the regex etc. No JavaScript is needed for server-side validation.

how to make a regex string reject a blank field [duplicate]

This question already has answers here:
How can I validate an email address in JavaScript?
(79 answers)
Closed 8 years ago.
I am very new to coding so go easy.
I am trying to make a email validation form but it needs to reject a blank cell (input box) sorry for being so bad at coding..... i also was going to use a regex
it has to be alpanumeric#alpanumeric.alpanumeric
sorry

The correct behavior in this case would be to perform a "pre-check" on fields before actually executing some more complex validation (eg: regular expressions).
The logic would look something like this:
valid_email = false;
email = strip_leading_trailing_spaces( email ); // don't forget to cleanup user input
if ( email != "" ) {
// perform regex testing here, set valid_email to false if failed
}
// handle "valid_email" variable here
It's worth noting here that any client side validation should be duplicated to/re-checked on the server as any user with a little knowledge in JS could easily bypass any validation done on the clients computer.

You don't need a regex if you are just checking to see if it's empty:
<input type=text id=email><button onClick="validate()">Validate</button>
<script language="javascript">
function validate() {
if ($("#email").val().length == 0) {
alert("Enter an email address");
}
}
</script>

with a regexp :
var valid_email = ! email.match( /^\s*$/ ) ;
If there's only spaces and tabs or nothing then valid_email = false
demo : http://regex101.com/r/iX8lF7/1

regular expression in email validation javascript

I am doing email regular expression validation for the email and I am stuck on one point using
following expression if user enter something like abc.abc then this expression works fine but when user enters advxyz#pqr.com then it doesn't work
var myreg = new RegExp(/([a-z0-9.]+)#([a-z0-9]+)\.([a-z0-9]+)/i);
var patter = myreg.test(document.getElementById("email").value)
alert(patter)
if(patter == false){
errorMsg.push("email Formate Error Ex:firstname.lastname#abc.com");
}
I want that user must enter his email in this formate like firstname.lastname#abc.com/.ca/.org

var pattern = /^[a-z0-9]+\.[a-z0-9]+#[a-z0-9]+\.[a-z]+$/i;
pattern.test('firstname.lastname#abc.com');
// returns true;
pattern.test('jsmith#abc.com');
// returns false;
pattern.test("abc.abc");
// returns false;

Using Regular Expressions is probably the best way.
Here's an example
(live demo):
function validateEmail(email) {
var re = /^(([^<>()[\]\\.,;:\s#\"]+(\.[^<>()[\]\\.,;:\s#\"]+)*)|(\ ".+\"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
return re.test(email);
}
But keep in mind that one should not rely only upon JavaScript validation. JavaScript can easily be disabled. This should be validated on the server side as well.
Source

This work Perfectly for me.
/^[a-zA-Z]([a-zA-Z0-9_\-])+([\.][a-zA-Z0-9_]+)*\#((([a-zA-Z0-9\-])+\.){1,2})([a-zA-Z0-9]{2,40})$/;

Hope this is helpful in resolving the issue \b[A-Z0-9._%-]+#[A-Z0-9.-]+.[A-Z]{2,4}\b
Its case sensitive.

Pattern for to validate email address is:
/^([a-zA-Z0-9_.-])+\#(([a-zA-Z0-9-])+.)+([a-zA-Z0-9]{2,4})+$/;
use this pattern in Regex. and you can validate any email..

Validation function for multiple inputs

I have a form with 2 number inputs and I am trying to validate it using the jQuery Validation plugin. I want to allow the form to be submitted only if the sum of the values is less than or equal to 10. For example, I want to allow 3 and 6, but not 7 and 8. How can I do this?
I was able to come up with something that works but I think it is inelegant and fragile to arbitrarily apply the rule to one input and use an attribute on that input to refer to the other input. I looked in the documentation for the plugin and I don't see any way of defining a validator that is meant to be used on more than one input. Can anyone think of a simpler way?

As far as the jquery validation plugin. No. A simpler way. Yes write your own in plain javascript.
function mySubmitfuntcion()
{
var myvar1 = document.GetElementById("1").value;
var myvar2 = document.GetElementById("2").value;
if(myvar1 + myvar2 <= 10) {
return true;
}
else {
alert("Please enter valid values");
return false;
} // end if
} // end function
returning false stops the mySubmitfunction() from completing.
In my experience writing custom validation scripts works better because you have more control. Remember to add the validation function to a button or the forms onsubmit event.

How can I validate a form field value against a variable with jQuery Validate?

I'm sure there must be a simple solution to this..
I simply want to create a rudimentary human verification tool for an online form. In pseudo-code, something like
$answer = "foo";
if (form['question'] == $foo){
// Proceed
} else {
// Fail
}
The jQuery docs seem to have an equalTo method but this is to compare a form field with another form value..
Any tips greatly appreciated! :)

You need to have a look at JQuery Validation plugin at http://docs.jquery.com/Plugins/validation. Consider the following example:
You may change the rules as explained in the plugin to implement your custom validations.

Have you looked at this plugin? You can use it to make fields required, validate for certain value types (number, string, credit card, etc), and I believe you can write callback functions to validate for specific values.
http://docs.jquery.com/Plugins/validation

var answer = 'foo';
if ($('#question').val() == answer) {
// Proceed
} else {
// Fail.
}