Disabling Form Elements
In some cases, you may not want visitors to use certain parts of your form. For example, you might want to disable a submit button until all the required fields have been filled out.
To disable a form element:
In the form element's tag, type disabled="disabled".
Figure 17.59. When the visitor first views the form, nothing is selected and the submit button is disabled.
In HTML, you can just use disabled by itself. XHTML requires the redundant value.
If you disable a form element, its keyboard shortcut is also disabled. For more information on keyboard shortcuts, consult Adding Keyboard Shortcuts on page 278.