javascript - Using querySelectorAll(). Is the result returned by the method ordered?

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javascript - Using querySelectorAll(). Is the result returned by the method ordered?

posted Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

javascript - Using querySelectorAll(). Is the result returned by the method ordered?

I'm trying to make a js code that works with multiple pages. I'm trying to use querySelectorAll() to obtain the elements form the DOM.

I need the elements to be ordered. In order to do that I may use xPath or selectors (I'd prefer to use selectors but xPath is also ok). The problem is:
Are the elements in the NodeList returned by querySelectorAll() ordered against the order that the tags appear in the HTML?

Note: I'd like to add the tag: querySelectorAll

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深蓝 · Answer 1 · 2021-10-23T17:57:47+0000

The returned node list is ordered. A quick test proved it:

document.querySelectorAll("body, head")[0]; //Returned [object HTMLHeadElement]

Obviously, the <head> tag appears before <body> in a HTML document. The first element of the NodeList is also a <head> element, even if the selector shows body before `head.

From http://www.w3.org/TR/selectors-api/#queryselectorall:

The querySelectorAll() method on the NodeSelector interface must, when invoked, return a NodeList containing all of the matching Element nodes within the node’s subtrees, in document order. If there are no such nodes, the method must return an empty NodeList.

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javascript - Using querySelectorAll(). Is the result returned by the method ordered?

javascript - Using querySelectorAll(). Is the result returned by the method ordered?

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