change option selected - Page 2

Arbitrator · 03-13-2013, 06:53 AM

Quote:

Originally Posted by Philip M

A select list option cannot have an id.

Quote:

Originally Posted by WolfShade

Options don't have "ID".. text, value.. I think that's it.

Quote:

Originally Posted by Philip M

Yes, I think that has been made clear already. Text, value and selectedIndex.

This isn't true; option elements can have id attributes. See:

As far as I can tell, there's no longer a restriction on characters allowed in IDs other than spaces in HTML5, so that would make this solution viable:

Code:

<!doctype html>
<html lang="en-US">
	<head>
		<title>Demo Document</title>
	</head>
	<body>
		<select>
			<option value="">-First Select Color-</option>
			<option id="1993" value="1993">N:Navy</option>
			<option id="1997" value="1997">BK:Black</option>
			<option id="2200" value="2200">O:Orchid</option>
		</select>
		<script>
			function select_option(option_value) {
				document.getElementById(option_value).selected = true;
			}
			select_option("1993");
		</script>
	</body>
</html>

Logic Ali's solution is a more straightforward (and still standards-compliant) though.

Philip M · 03-13-2013, 08:36 AM

Quote:

Originally Posted by Arbitrator

This isn't true; option elements can have id attributes. See:

You tell me something. But I have never had any occasion to use an option id.

But surely an id may not start with a number?
From the HTML 4 specification: ID and NAME tokens must begin with a letter ([A-Za-z])

I tested your script and - amazingly it works in HTML4 (no !DOCTYPE)! Why is that?

I read that HTML5 gets rid of the additional restrictions on the id attribute. The only requirements left — apart from being unique in the document — are that the value must contain at least one character (can’t be empty), and that it can’t contain any space characters.

Could you devise an example where an option id is really useful?

Arbitrator · 03-13-2013, 09:52 AM

Quote:

Originally Posted by Philip M

You tell me something. But I have never had any occasion to use an option id.

Well, now you can use them to your heart's content.

Quote:

Originally Posted by Philip M

But surely an id may not start with a number?
From the HTML 4 specification: ID and NAME tokens must begin with a letter ([A-Za-z])

In HTML4 and XHTML 1/1.1, there is that restriction, yes. This is a legacy, SGML-based restriction though.

I can't find anything in the HTML5 specs (WHATWG or W3C) or the spec that those two link to relating to IDs (the WHATWG's DOM Living Standard spec) that indicates that this restriction persists.

Quote:

Originally Posted by Philip M

I tested your script and - amazingly it works in HTML4 (no !DOCTYPE)! Why is that?

Well, the id attribute for option elements is defined in the HTML4 spec, so it's not really surprising.

Quote:

Originally Posted by Philip M

Could you devise an example where an option id is really useful?

No, not really, unless maybe it works better than Logical Ali's solution in the situation that Old Pedant mentioned (compatibility with old versions of Firefox). I never said that it was particularly useful, just that it wasn't disallowed.

Thankfully, there's no need to remember which elements id attributes are allowed on anymore; HTML5 simplifies things by permitting IDs for everything instead of carving out exceptions like HTML4 did.

Philip M · 03-13-2013, 11:19 AM

Quote:

Originally Posted by Arbitrator

Well, the id attribute for option elements is defined in the HTML4 spec, so it's not really surprising.

I was referring to your ids being numbers, said to be illegal in HTML4.

I have to say that in future I shall still avoid assigning ids which start with an number. That ensures backwards compatibility, and I don't see the restriction as significant. I don't see any reason or situation where it is necessary to use an id starting with a number. But old habits die hard.