An email address must contain at least a ‘@’ sign and a dot (.).
Also, the ‘@’ must not be the first character of the email address, and the last dot must at least be one character after the ‘@’ sign.
Form validation normally used to occur at the server, after the client had entered all the necessary data and then pressed the Submit button.
If the data entered by a client was incorrect or was simply missing, the server would have to send all the data back to the client and request that the form be resubmitted with correct information.
Now we will see how we can validate our entered form data before submitting it to the web server.
The following example shows how to validate an entered email address.
HP 5.3.3 and 5.2.14 had a bug ( related to FILTER_VALIDATE_EMAIL, which resulted in segfault when validating large values.
Simple and safe workaround for this is using strlen() before filter_val().
In the above form, we are calling validate() to validate data when onsubmit event is occurring.
The following code shows the implementation of this validate() function.