RegEx Example question

williamjwayne · February 17th, 2009, 04:51 PM

Hi:

I am referring to the example on p.222 at the very bottom (the two alerts). The books says that the isValidEmail function can be called using the alerts. I don't understand how that works. It seems to imply this function can be called by inserting the alerts. I don't see how that would work. What am I missing here. Any help is appreciated.

zeronexxx · February 17th, 2009, 06:34 PM

hi

i am afriad i don't have the book but if you post more details i will be able to help you .

Thanks

Old Pedant · February 17th, 2009, 09:12 PM

Agree w/ zeronexxx, but I *suspect* they simply mean you can do

Code:

if ( ! isValidEmail( someFormField ) ) alert("Doofus...I wanted your email address");

But you'll almost always get more responses (and correct responses) if you show the actual code so that those without the book can understand your question.

zeronexxx · February 17th, 2009, 09:56 PM

or may be something like

PHP Code:


			

function isValidEmail(EmailField){
    var regex = /[a=zA-Z0-9_\-]+@[a-zA-Z0-9\-.]/;
    if(regex.match(EmailField.value)){
       return "this is valid email";
    }else{
       return "this email is invalid";
    }
}


alert(isValidEmail(someEmailField));

Old Pedant · February 17th, 2009, 10:07 PM

Good guess!

Of course, it's weird if either of us is right, because then how does the validation cancel the form submittal???

Ugh.

williamjwayne · February 18th, 2009, 02:46 PM

Thank you all for the responses!

My regrets for not listing all information. The information I was questioning is located on p.222 of JavaScript for Web Developers, Nicholas C. Zakas. In it the author discusses validating e-mail addresses using RegEx techniques. He discusses the major email formats and offers a RegEx validation solution:

function isValidEmail(sText) {
var reEmail = /^(?:\w+\.?)*\w+@(?:\w+\.)+\w+$/;
return reEmail.test(sText);
}

He then goes on to add in the next line:

"This function can be called like so:

alert([email protected]); //outputs "true"

alert(john.doe@somewhere.); //outputs "false" "

(The underlining on the email addresses are not in the book but were added by default in this editor.)

And that is where my confusion comes in. I am unaware of how the function can be called given the code as laid out in the book. Of course the RegEx works but I don't see how the function can be invoked using just an alert. I thought it was just a typo but the errata pages for the book does not address it. Do you have any info that can shed light?

Regards,
Bill Wayne

zeronexxx · February 18th, 2009, 04:08 PM

Hi Bill

I am afraid that what you have expressed above clearly is not the case, following is the actual code. I downloaded the code and here is the full code.

PHP Code:


			
<html>
    <head>
        <title>E-mail Example</title>
        <script type="text/javascript">
    

                function isValidEmail(sText) {
                    var reEmail = /^(?:\w+\.?)*\w+@(?:\w+\.)+\w+$/;
                    return reEmail.test(sText);
                }

                
                function validate() {
                    var oInput1 = document.getElementById("txt1");
                    if (isValidEmail(oInput1.value)) {
                        alert("Valid");
                    } else {
                        alert("Invalid!");
                    }

                }
        </script>
    </head>
    <body>
        <p>E-mail Address: <input type="text" id="txt1" /><br />
        <input type="button" value="Validate" onclick="validate()" /></p>
       
    </body>
</html>

Hopefully the confusion is clear now?

Regards

williamjwayne · February 18th, 2009, 09:57 PM

Thanks for the info regarding the errata correction -- I had seen that so I guess my question has been answered. I just wanted to make sure that there was not something that I was missing.

Regards,
Bill Wayne