How to validate email field in javascript?

Question

This is the script I use for form validation:

<script language="JavaScript">

function formCheck(formobj){
    var fieldRequired = Array("Name", "Email", "Phone", "comments");
    var fieldDescription = Array("Name", "Email", "Phone", "Comments");
    var alertMsg = "Please complete the following fields:\n";

    var l_Msg = alertMsg.length;

    for (var i = 0; i < fieldRequired.length; i++){
        var obj = formobj.elements[fieldRequired[i]];
        if (obj){
            switch(obj.type){
            case "select-one":
                if (obj.selectedIndex == -1 || obj.options[obj.selectedIndex].text == ""){
                    alertMsg += " - " + fieldDescription[i] + "\n";
                }
                break;
            case "select-multiple":
                if (obj.selectedIndex == -1){
                    alertMsg += " - " + fieldDescription[i] + "\n";
                }
                break;
            case "text":
            case "textarea":
                if (obj.value == "" || obj.value == null){
                    alertMsg += " - " + fieldDescription[i] + "\n";
                }
                break;
            default:
            }
            if (obj.type == undefined){
                var blnchecked = false;
                for (var j = 0; j < obj.length; j++){
                    if (obj[j].checked){
                        blnchecked = true;
                    }
                }
                if (!blnchecked){
                    alertMsg += " - " + fieldDescription[i] + "\n";
                }
            }
        }
    }

    if (alertMsg.length == l_Msg){
        return true;
    }else{
        alert(alertMsg);
        return false;
    }
}
// -->
</script>


<form onsubmit="return formCheck(this);" action="/capture.weblead" method="post">
First Name: <input type=text name="FirstName" size="25"><br>
Last Name: <input type=text name="LastName" size="25"><br>
<input type=submit value="Submit Form">
</form>

It works great except it doesn't validate for a REAL email address. How to alter this form so that it does?

The script can't contain any dollar symbols otherwise Tomcat (my server environment) crashes.

duplicate: stackoverflow.com/questions/46155/… stackoverflow.com/questions/2783672/email-validation-javascript stackoverflow.com/questions/940577/… — Mauricio Scheffer
– Mauricio Scheffer, Commented Jun 21, 2010 at 17:49
Tomcat can definitely serve scripts containing "$" characters. Also it's hard to verify syntax for an email address, and impossible to tell whether it's real. — Pointy
– Pointy, Commented Jun 21, 2010 at 17:51

rich code · Accepted Answer · 2011-08-30 08:18:24Z

16

You can use regex in javascript

function is_email(email){      
var emailReg = /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$/;
return emailReg.test(email); }

http://richwd.com/email-javascript

answered Aug 30, 2011 at 8:18

rich code

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Comments

Keith Adler · Accepted Answer · 2010-06-21 18:03:34Z

1

I would suggest you use jQuery and the Validation plug-in:

http://bassistance.de/jquery-plugins/jquery-plugin-validation/

It's flexible, reliable and easy to use.

answered Jun 21, 2010 at 18:03

Keith Adler

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Comments

wnrph · Accepted Answer · 2010-06-21 18:18:46Z

This is a quick and dirty solution. Modify the value of the emailRegexp variable to suit your needs. There are already some examples here. As Pointy pointed out, it's generally better to have false positives than false negatives.

function formCheck(formobj){
    var fieldRequired = Array("Name", "Email", "Phone", "comments");
    var fieldDescription = Array("Name", "Email", "Phone", "Comments");
    var alertMsg = "Please complete the following fields:\n";
    var emailRegexp =/@/;

    var l_Msg = alertMsg.length;

    for (var i = 0; i < fieldRequired.length; i++){
        var obj = formobj.elements[fieldRequired[i]];
        if (obj){
            switch(obj.type){
            case "select-one":
                if (obj.selectedIndex == -1 || obj.options[obj.selectedIndex].text == ""){
                    alertMsg += " - " + fieldDescription[i] + "\n";
                }
                break;
            case "select-multiple":
                if (obj.selectedIndex == -1){
                    alertMsg += " - " + fieldDescription[i] + "\n";
                }
                break;
            case "text":
            case "textarea":
                if ( obj.value == "" || 
                     obj.value == null || 
                     ( fieldRequired[i] == "Email" && !obj.value.match(emailRegexp) ))
                {

                    alertMsg += " - " + fieldDescription[i] + "\n";
                }


                break;
            default:
            }
            if (obj.type == undefined){
                var blnchecked = false;
                for (var j = 0; j < obj.length; j++){
                    if (obj[j].checked){
                        blnchecked = true;
                    }
                }
                if (!blnchecked){
                    alertMsg += " - " + fieldDescription[i] + "\n";
                }
            }
        }
    }

    if (alertMsg.length == l_Msg){
        return true;
    }else{
        alert(alertMsg);
        return false;
    }
}

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