In HTML4.01:
Name Attribute
- Valid only on
<a>,<form>,<iframe>,<img>,<map>,<input>,<select>,<textarea> - Name does not have to be unique, and can be used to group elements together such as radio buttons & checkboxes
- Can not be referenced in URL, although as JavaScript and PHP can see the URL there are workarounds
- Is referenced in JavaScript with
getElementsByName() - Shares the same namespace as the
idattribute - Must begin with a letter
- According to specifications is case sensitive, but most modern browsers don’t seem to follow this
- Used on form elements to submit information. Only input tags with a
nameattribute are submitted to the server
Id Attribute
- Valid on any element except
<base>,<html>,<head>,<meta>,<param>,<script>,<style>,<title> - Each Id should be unique in the page as rendered in the browser, which may or may not be all in the same file
- Can be used as anchor reference in URL
- Is referenced in CSS or URL with
#sign - Is referenced in JavaScript with
getElementById(), and jQuery by$(#<id>) - Shares same name space as name attribute
- Must contain at least one character
- Must begin with a letter
- Must not contain anything other than letters, numbers, underscores (
_), dashes (-), colons (:), or periods (.) - Is case insensitive
In (X)HTML5, everything is the same, except:
Name Attribute
- Not valid on
<form>any more - XHTML says it must be all lowercase, but most browsers don’t follow that
Id Attribute
- Valid on any element
- XHTML says it must be all lowercase, but most browsers don’t follow that
This question was written when HTML4.01 was the norm, and many browsers and features were different from today.