JavaScript form validation ensures that information entered into website form fields is valid before processing. It checks for missing symbols, required fields, and valid formats. However, it can’t catch all mistakes and relies on the user to enter accurate information. JavaScript support can be turned off, allowing invalid information to be processed.
JavaScript® form validation refers to using the JavaScript® language to write scripts that help ensure that the information visitors to a website enter into form fields on a form is valid before it is processed. For example, no email address can be considered valid if the “@” symbol is missing, and all types of valid phone numbers consist of more than one digit. Front-end and back-end web developers often operate JavaScript® form validation to legitimately collect and process information from website visitors for a variety of purposes, such as receiving email via a contact form. The minimum data that needs to be collected includes the visitor’s name, email address and message so that the webmaster or person to whom the email is addressed knows who contacted, at what address and -mail should respond and the content of the visitor’s message.
Typical information that a web developer might perform JavaScript® form validation for includes checking the length of a password; compare the confirmation password with the proposed password; and checking the area code, length, and expiration date of a credit card. Depending on the purpose and type of information requested from the visitor, JavaScript® form validation could also be used to verify that all required form fields not only contain data that appears valid, but that the field is not left blank. Making sure information is not missing can be just as important as verifying its validity. While JavaScript® does a good job of checking information to see if it seems valid, the fact is that this is the only thing it can do. That is why online forms must be filled in accurately by the visitor.
If a mistake is made when typing a character of an email address or a digit of a phone number, the script will see the information as valid as long as the format in which it was entered appears to be valid. Millions of websites rely on JavaScript® form validation, which attests to the effectiveness of the many well-written scripts that have been coded in this language for client-side validation of user data. This does not mean, however, that there are no disadvantages to validating or at least using it as the only way to verify the information that website visitors enter into form fields. JavaScript® support can be turned on and off by the client computer operator by changing the configuration settings within the web browser.
JavaScript® support is almost always on by default, and the average person doesn’t know how to turn it off in their browser or even if it can be turned off. However, if language support is turned off, scripts of any kind written in the language cannot run, allowing invalid information to be processed. Some websites advise visitors to enable JavaScript® if it is disabled.
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