I want to make a CSS selector for a class which starts with a whitespace, but I don't know how. For example: <table class=" example">…</table>.
Any leading or trailing spaces in the value of a class attribute are meaningless for targeting purposes. This: class=" example" is equivalent to this: class="example".
There is no need for a special selector that factors in the space.
From the HTML 5 spec:
2.4.7 Space-separated
tokens
A string containing a set of space-separated tokens may have leading
or trailing space characters.
Space characters are necessary, however, for separating multiple values in a class attribute.
3.2.5.7 The class
attribute
The attribute, if specified, must have a value that is a set of
space-separated tokens representing the various classes that the
element belongs to.
CSS classnames are single words; spaces just separate different classnames.
You want .example.
Whitespace at the start and end of a value for the class attribute is insignificant for the purposes of class selectors. class=" example" is valid HTML and equivalent to class="example", class="example " and even class=" example " for the purposes of the .example class selector.
Therefore the selector you're looking for is simply .example.
The only situation where it makes a difference in selectors is with attribute selectors: [class~="example"] will match all of the given examples, but [class="example"] will only match class="example". (This means, consequently, that if you have some esoteric reason to want to match the element only when its class attribute has a leading space, you can use either [class^=" example"] or [class=" example"], but you most likely just want a regular class selector.)
Here is the div:
<div class='something' id='1'>
I got 9 of them with different positions on page so in the .css file I do:
div#1.something {
code...
}
And the thing is that it won't work, I know this is the proper selector but I have also tried div.something#1 and it also doesn't work, as expected. I think there is something wrong with ID as a number, should I change it or there is a way?
Although it's allowed to set a class or id to begin with a digit in HTML5, but it's not allowed in CSS, see the spec:
HTML5: 3.2.5.1 The id attribute
... There are no other restrictions on what form an ID can take; in particular, IDs can consist of just digits, start with a digit, start with an underscore, consist of just punctuation, etc. ...
CSS: 4.1.3 Characters and case
... they cannot start with a digit, two hyphens, or a hyphen followed by a digit. Identifiers can also contain escaped characters and any ISO 10646 character as a numeric code ...
i.e.
<div id="1"> is valid HTML, but you cannot target it with #1 {...} in CSS.
However, you can use [id="1"] {...} or escape it #\31 {...}
Please try this:
You can call either by class or ID.
div.something {
code...
}
or
div#1 {
code...
}
Change id="1" to id="one" since you cannot use numbers in CSS to select an id or class. Then just use div#one { // CSS Here } since you don't really need to include the class. After all you can only have one id with a specific name per page.
Can I have multiple values in one HTML "data-" element? Similar to how a class can have multiple class names.
If possible, I would like to create a CSS/JS library that makes use of one "data-" element to house all of the library styles. For example:
<div data-library-name="xs-hidden col-md-10 col-xl-8 big-hero"></div>
That way, any of the programmers custom style rules can go into the elements class. My reasoning for this is to make readability easier, so together it would look like:
<div class="custom-style another-style" data-library-name="xs-hidden col-md-10 col-xl-8 big-hero"></div>
Can I have multiple values in one HTML "data-" element?
You can have a string. The spec doesn't define any particular format for the data in the attribute, which is designed to be processed by site specific JavaScript.
Similar to how a class can have multiple class names.
The class attribute takes a space separated list of classes.
Your JavaScript can your_data_attribute_value.split(" "); if you like.
Handling this with CSS would use the ~= attribute selector.
[att~=val]
Represents an element with the att attribute whose value is a whitespace-separated list of words, one of which is exactly "val". If "val" contains whitespace, it will never represent anything (since the words are separated by spaces). Also if "val" is the empty string, it will never represent anything.
AFAIK, I don't think data- attributes can convert that to an array. Instead, I think it'll interpret it as one value, but it is allowed.
If you want to do that, you'll probably have to split() it later in JavaScript into an array of usable values.
See this example on JSFiddle.net.
CSS has the shortcut .class selector but it actually is parsing the attribute named "class" as a list for space separated values. This is supported in the non-shortcut form by the following attribute selector:
[att~=val]
Represents an element with the att attribute whose value is a white space-separated list of words, one of which is exactly "val". If "val" contains white space, it will never represent anything (since the words are separated by spaces). If "val" is the empty string, it will never represent anything either.
Ref: http://www.w3.org/TR/CSS2/selector.html#class-html
As your question is tagged CSS you're perhaps looking for that. The rules how the parsing of attribute values is done is given in that document as well, so in case the javascript library you're trying to use on this (if any) won't cover that, it should be easy to add:
var list = $("div").data("library-name").split(/\s+/);
^^^^^^^^^^^^
This split with the white-space regular expression parses the string attribute value into an array with javascript and the Jquery library (for accessing the DOM and the data attribute).
How can I match the contents of all divs that have a specific class. For example:
<div class="column-box-description paddingT05">content</div>
Generally, you shouldn't do this with regex unless you can make strong assumptions about the text you're matching; you'll do better with something that actually parses HTML.
But, if you can make these stronger assumptions, you can use:
<div class="[^"]*?paddingT05[^"]*?">(.*?)<\/div>
The key part is the reluctant quantifier *? which matches the minimal text possible (i.e. it doesn't greedily eat up the </div>.
You can do something like this:
<div.*class\s*=\s*["'].*the_class_you_require_here.*["']\s*>(.*)<\/div>
Replace "the_class_you_require_here" with a class name of your choosing. The div content is in the first group resulted from this expesion. You can read on groups here: http://www.regular-expressions.info/brackets.html
I understand that an id must be unique within an HTML/XHTML page.
For a given element, can I assign multiple ids to it?
<div id="nested_element_123 task_123"></div>
I realize I have an easy solution with simply using a class. I'm just curious about using ids in this manner.
No. From the XHTML 1.0 Spec
In XML, fragment identifiers are of
type ID, and there can only be a
single attribute of type ID per
element. Therefore, in XHTML 1.0 the
id attribute is defined to be of type
ID. In order to ensure that XHTML 1.0
documents are well-structured XML
documents, XHTML 1.0 documents MUST
use the id attribute when defining
fragment identifiers on the elements
listed above. See the HTML
Compatibility Guidelines for
information on ensuring such anchors
are backward compatible when serving
XHTML documents as media type
text/html.
Contrary to what everyone else said, the correct answer is YES
The Selectors spec is very clear about this:
If an element has multiple ID attributes, all of them must be treated as IDs for that element for the purposes of the ID selector.Such a situation could be reached using mixtures of xml:id, DOM3 Core, XML DTDs, and namespace-specific knowledge.
Edit
Just to clarify: Yes, an XHTML element can have multiple ids, e.g.
<p id="foo" xml:id="bar">
but assigning multiple ids to the same id attribute using a space-separated list is not possible.
No. While the definition from W3C for HTML 4 doesn't seem to explicitly cover your question, the definition of the name and id attribute says no spaces in the identifier:
ID and NAME tokens must begin with a letter ([A-Za-z]) and may be followed by any number of letters, digits ([0-9]), hyphens ("-"), underscores ("_"), colons (":"), and periods (".").
My understanding has always been:
IDs are single use and are only applied to one element...
Each is attributed as a unique identifier to (only) one single element.
Classes can be used more than once...
They can therefore be applied to more than one element, and similarly yet different, there can be more than one class (i.e., multiple classes) per element.
No. Every DOM element, if it has an id, has a single, unique id. You could approximate it using something like:
<div id='enclosing_id_123'><span id='enclosed_id_123'></span></div>
and then use navigation to get what you really want.
If you are just looking to apply styles, class names are better.
You can only have one ID per element, but you can indeed have more than one class. But don't have multiple class attributes; put multiple class values into one attribute.
<div id="foo" class="bar baz bax">
is perfectly legal.
No, you cannot have multiple ids for a single tag, but I have seen a tag with a name attribute and an id attribute which are treated the same by some applications.
No, you should use nested DIVs if you want to head down that path. Besides, even if you could, imagine the confusion it would cause when you run document.getElementByID(). What ID is it going to grab if there are multiple ones?
On a slightly related topic, you can add multiple classes to a DIV. See Eric Myers discussion at,
http://meyerweb.com/eric/articles/webrev/199802a.html
I'd like to say technically yes, since really what gets rendered is technically always browser-dependent. Most browsers try to keep to the specifications as best they can and as far as I know there is nothing in the CSS specifications against it. I'm only going to vouch for the actual HTML, CSS, and JavaScript code that gets sent to the browser before any other interpreter steps in.
However, I also say no since every browser I typically test on doesn't actually let you.
If you need to see for yourself, save the following as a .html file and open it up in the major browsers. In all browsers I tested on, the JavaScript function will not match to an element. However, remove either "hunkojunk" from the id tag and all works fine.
Sample Code
<html>
<head>
</head>
<body>
<p id="hunkojunk1 hunkojunk2"></p>
<script type="text/javascript">
document.getElementById('hunkojunk2').innerHTML = "JUNK JUNK JUNK JUNK JUNK JUNK";
</script>
</body>
</html>
Nay.
From 3.2.3.1 The id attribute:
The value must not contain any space characters.
id="a b" <-- find the space character in that VaLuE.
That said, you can style multiple IDs. But if you're following the specification, the answer is no.
From 7.5.2 Element identifiers: the id and class attributes:
The id attribute assigns a unique identifier to an element (which may
be verified by an SGML parser).
and
ID and NAME tokens must begin with a letter ([A-Za-z]) and may be
followed by any number of letters, digits ([0-9]), hyphens ("-"),
underscores ("_"), colons (":"), and periods (".").
So "id" must be unique and can't contain a space.
No.
Having said that, there's nothing to stop you doing it. But you'll get inconsistent behaviour with the various browsers. Don't do it. One ID per element.
If you want multiple assignations to an element use classes (separated by a space).
Any ID assigned to a div element is unique.
However, you can assign multiple IDs "under", and not "to" a div element.
In that case, you have to represent those IDs as <span></span> IDs.
Say, you want two links in the same HTML page to point to the same div element in the page.
The two different links
<p>Exponential Equations</p>
<p><Logarithmic Expressions</p>
Point to the same section of the page
<!-- Exponential / Logarithmic Equations Calculator -->
<div class="w3-container w3-card white w3-margin-bottom">
<span id="exponentialEquationsCalculator"></span>
<span id="logarithmicEquationsCalculator"></span>
</div>
The simple answer is no, as others have said before me. An element can't have more than one ID and an ID can't be used more than once in a page. Try it out and you'll see how well it doesn't work.
In response to tvanfosson's answer regarding the use of the same ID in two different elements. As far as I'm aware, an ID can only be used once in a page regardless of whether it's attached to a different tag.
By definition, an element needing an ID should be unique, but if you need two ID's then it's not really unique and needs a class instead.
That's interesting, but as far as I know the answer is a firm no. I don't see why you need a nested ID, since you'll usually cross it with another element that has the same nested ID. If you don't there's no point, if you do there's still very little point.
Classes are specially made for this, and
here is the code from which you can understand it:
<html>
<head>
<style type="text/css">
.personal{
height:100px;
width: 100px;
}
.fam{
border: 2px solid #ccc;
}
.x{
background-color:#ccc;
}
</style>
</head>
<body>
<div class="personal fam x"></div>
</body>
</html>
ID's should be unique, so you should only use a particular ID once on a page. Classes may be used repeatedly.
Check HTML id Attribute (W3Schools) for more details.
I don´t think you can have two Id´s but it should be possible. Using the same id twice is a different case... like two people using the same passport. However one person could have multiple passports... Came looking for this since I have a situation where a single employee can have several functions. Say "sysadm" and "team coordinator" having the id="sysadm teamcoordinator" would let me reference them from other pages so that employees.html#sysadm and employees.html#teamcoordinator would lead to the same place... One day somebody else might take over the team coordinator function while the sysadm remains the sysadm... then I only have to change the ids on the employees.html page ... but like I said - it doesn´t work :(