What's the difference between disabled="disabled" and readonly="readonly" for HTML form input fields?
I have read a bit on this, but I can't seem to find anything solid about how different browsers treat things.
Answer
A readonly element is just not editable, but gets sent when the according form submits. A disabled element isn't editable and isn't sent on submit. Another difference is that readonly elements can be focused (and getting focused when "tabbing" through a form) while disabled elements can't.
Read more about this in this great article or the definition by w3c. To quote the important part:
Key Differences
The Disabled attribute
- Values for disabled form elements are not passed to the processor method. The W3C calls this a successful element.(This works similar to form check boxes that are not checked.)
- Some browsers may override or provide default styling for disabled form elements. (Gray out or emboss text) Internet Explorer 5.5 is particularly nasty about this.
- Disabled form elements do not receive focus.
- Disabled form elements are skipped in tabbing navigation.
The Read Only Attribute
- Not all form elements have a readonly attribute. Most notable, the
<SELECT>,<OPTION>, and<BUTTON>elements do not have readonly attributes (although they both have disabled attributes)- Browsers provide no default overridden visual feedback that the form element is read only. (This can be a problem… see below.)
- Form elements with the readonly attribute set will get passed to the form processor.
- Read only form elements can receive the focus
- Read only form elements are included in tabbed navigation.