Otherwise a browser with Java Script disabled, or a hacker trying to compromise your site, can easily submit invalid data. The first test in the example is therefore only necessary in order to provide a different error message when the input is blank.The purpose of a form validation script is to return a boolean value ('s to reference form fields, but that can lead to namespace conflicts and why make things more complicated than necessary.Radio buttons are implemented as if they were an array of checkboxes.To find out which value (if any) has been selected, you need to loop through the array until you find which one has been selected: In the case of a single radio button we have nothing to loop through so just return either it's value, if the radio button is checked, or false.Each field in the form can have zero one or more validations. More info & downloads where Do My Validation One() and Do My Validation Two() are custom functions for validation.For example, you can have an input field that should not be empty, should be less than 25 chars and should be alpha-numeric. In some dynamically programmed pages, it may be required to change the validations in the form at run time.In other words if the first condition fails, the second condition will not be tested and so forth.Only when all conditions have been satisfied do we reach the command, in which case the form will be submitted.
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.The Java Script class presented here makes the form validations many times easier.The script has a catalog of almost all the common validation types built-in.Validating form input with Java Script is easy to do and can save a lot of unnecessary calls to the server as all processing is handled by the web browser.It can prevent people from leaving fields blank, from entering too little or too much or from using invalid characters.
I tested your first piece of code on a form and it does not work at all.