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.
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.
Otherwise a browser with Java Script disabled, or a hacker trying to compromise your site, can easily by-pass client-side validation.
For an alternative approach to client-side form validation, without Java Script, check out our new article on HTML5 Form Validation which is available now in most modern browsers. The first test in the example is therefore only necessary in order to provide a different error message when the input is blank.
To take things a step further you can even explore Ajax Form Validation which lets you supply real-time feedback using server-side scripts triggered by Java Script events.
The team at have made a video based on this article as a part of their Java Script training lessons which you can view below. Would be great if you could post full examples of code including form and not just pieces that fit into the greater framework of code.
Tried setting it up on onsubmit on both form and button and no go.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.When the form is submitted - either by hitting Enter or clicking on the Submit button - the to abort (cancel) the form submission. In a real-life situation you will most likely have more fields to check, and more complicated conditions, but the principle remains the same.keyword, followed by a name, followed by parentheses ().Function names can contain letters, digits, underscores, and dollar signs (same rules as variables).