In more complicated forms you will want to set conditions on the form that combine multiple elements.For example, a text input that only needs to have a value if a checkbox is checked: Using simple logical operators and the functions supplied above you can do all sorts of client-side form validation.The purpose of a form validation script is to return a boolean value ( to reference form fields, but that can lead to namespace conflicts and why make things more complicated than necessary.
Most modern browsers now support HTML5 Form Validation making it possible to validate form elements without (or before) any Java Script is triggered.
The value of a text input box (or a textarea or password input) is available using the syntax that tells you which option has been selected.
Java Script is an object-oriented, interpretive language used with HTML to provide dynamic capabilities to otherwise static webpages.
A Java Script function included in an HTML page is processed and executed by the web browser.
All you need to do is extend the command, in which case the form will be submitted.
You'll see that the all validation scripts presented on this and subsequent pages adhere to the same basic format.
Nette Framework puts a great effort to be safe and since forms are the most common user input, Nette forms are as good as impenetrable.
All is maintained dynamically and transparently, nothing has to be set manually.
The illustration below shows this relationship: Note that the 'I' in selected Index needs to be capitalised - Java Script functions and variables are always case-sensitive. Read more about the humble checkbox in our HTML5 Checkbox Validation article.
Radio buttons are implemented as if they were an array of checkboxes.
Otherwise a browser with Java Script disabled, or a hacker trying to compromise your site, can easily by-pass client-side validation.