The DocumentFragment.querySelector()
method returns the first element, or null
if no matches are found, within the DocumentFragment
(using depth-first pre-order traversal of the document's nodes) that matches the specified group of selectors.
If the selector matches an ID and this ID is erroneously used several times in the document, it returns the first matching element.
If the selectors specified in parameter are invalid a DOMException
with a SYNTAX_ERR
value is raised.
In this basic example, the first element in the DocumentFragment
with the class "myclass
" is returned:
var el = documentfragment.querySelector(".myclass");
The string argument pass to querySelector
must follow the CSS syntax. To match ID or selectors that do not follow the CSS syntax (by using semicolon or space inappropriately for example), it's mandatory to escape the wrong character with a double back slash:
<div id="foo\bar"></div>
<div id="foo:bar"></div>
<script>
document.querySelector('#foo\bar')
document.querySelector('#foo\\\\bar')
document.querySelector('#foo:bar')
document.querySelector('#foo\\:bar')
</script>