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Validate multiple email id's using javascript

By , 28 Nov 2011
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I just used this on a website. Thanks.
But I made a change, using the ASP.NET CustomValidator and the ClientValidationFunction property.
<asp:customvalidator id="CustomValidator1" runat="server" clientvalidationfunction="validateMultipleEmailsCommaSeparated" xmlns:asp="#unknown">
 ErrorMessage="Not valid" ControlToValidate="toBox">
and the function updated to this:
function validateEmail(field) {
        var regex = /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,5}$/;
        return (regex.test(field)) ? true : false;
    function validateMultipleEmailsCommaSeparated(source, args) {
        var text = args.Value;
        if (text != '') {
            var result = text.split(",");
            for (var i = 0; i < result.length; i++) {
                var trimmed = result[i].trim();
                if (trimmed != '') {
                    if (!validateEmail(trimmed)) {
                        alert('Please check, `' + trimmed + '` email addresses not valid!');
                        return false;
        return true;
Since the ASP.NET ClientValidationFunction has a predefined set of parameters (source and arguments), I only made a small change and placed the separator right into the code. This also saved me from touching the onblur client event by myself.
Also, used the trim() to remove spaces before or after the email, that was causing problems if the users type the email addresses with a space after the comma.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Leonardo Paneque
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Leonardo loves to code with C# and thinks .NET platforms rocks.
He has a Master degree in Computer Sciences and likes to share code and ideas.
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Comments and Discussions

QuestionValidate multiple email id's using javascript PinmemberGiven Mbatsane7-Sep-12 2:58 
Thanks dude, that really helped me alot after i took me for a ride

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