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Are self-closing input tags valid in HTML 4?

According to http://www.w3.org/TR/html401/interact/forms.html#h-17.4, an input element should end with a single > and not a />. Though that most browsers can handle an input element that ends with />, is such an input element valid according to HTML syntax rules? In other words are elements like <input ... /> and <br /> valid in HTML 4?

(This question is about HTML and not XHTML!!!)

Solution

  • The syntax is valid in some places but doesn't mean the same as in XHTML, so don't use them.

    In HTML 4 <foo /> (where foo is the name of an element defined as EMPTY) means the same as <foo>> which means the same as <foo>&gt; (although almost no browser supports the syntax correctly, Emacs-W3 used to, but broke compatibility with the standard in favour of rendering so-called HTML compatible XHTML 1.0 documents correctly).

    This is, therefore, valid in places where you can have a &gt; such as anywhere you are allowed an <img> but not in other places (such as an <hr> that is a child element of the <body> (in Strict)).

    The interaction with the rules for optional start and end tags adds more complication. In a Transitional document, this is valid:

    <link …/>
<h1>Hello, world</h1>

    and means:

    <link>
</head>
<body>
&gt;
<h1>Hello, world</h1>

    This shorthand syntax could be useful, or at least a time saver, for things like:

    <title/The quick brown fox/

    instead of the more verbose: 

    <title>The quick brown fox</title>

    … but the syntax has never been well supported and the specification says it should be avoided.