identifier - Is it possible for an html5 document to have two ids? -


i wondering if html5 element can have 2 ids, this:

<button id="thing1" id="thing2" name="button1" onclick="change()">click here</button>

or this:

<button id="thing1, thing2" name="button1" onclick="change()">click here</button>

also, if 1 of ids said 1 thing, , other id said thing, 1 used?

tl;dr: no.

in versions of html, each element can have 1 id. see the spec:

the id attribute specifies element's unique identifier (id). [dom]

the value must unique amongst ids in element's home subtree , must contain @ least 1 character. the value must not contain space characters.

note: there no other restrictions on form id can take; in particular, ids can consist of digits, start digit, start underscore, consist of punctuation, etc.

note: element's unique identifier can used variety of purposes, notably way link specific parts of document using fragment identifiers, way target element when scripting, , way style specific element css.

identifiers opaque strings. particular meanings should not derived value of id attribute.

in examples gave, parser read first id. if tried this:

<button id="thing1,thing2" name="button1" onclick="change()">click here</button>

(with no space in id), still have single id, include comma: thing1,thing2.

note: there no reasons why want 2 id values not candidates using class or storing data in other way. example, in jquery, can do $('#some_id').data('foo', 'bar'); save piece of data named foo value bar , associate element id some_id. classes , data storage more flexible ids, anyway.

edit: keep in mind classes aren't css. can <button id="thing1" class="thing2 thing3 thing42"...> , use javascript (either plain or using library jquery) access button 1 or more of classes. class names can unique item , don't have used elsewhere or mentioned in css files.

here's a link jsfiddle example of how powerful classes , ids can when used together.


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