DOMNodeInserted -> Was #id inserted?
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From: Matt Kruse on 27 May 2010 09:07 Using a document listener on DOMNodeInserted, I'm trying to determine if an element with id="x" was inserted. So either the event.target.id=="x" or a child element of the one inserted has .id=="x". What is the best way to determine if #x is a child of the inserted element? Currently I'm doing: if ( element.querySelectorAll("#x").length==1 ) But that limits my browser compatibility. I'd like to support Firefox < 3.5, which lacks querySelectorAll. Matt Kruse
From: Martin Honnen on 27 May 2010 09:18 Matt Kruse wrote: > Using a document listener on DOMNodeInserted, I'm trying to determine > if an element with id="x" was inserted. So either the > event.target.id=="x" or a child element of the one inserted > has .id=="x". > > What is the best way to determine if #x is a child of the inserted > element? > > Currently I'm doing: > if ( element.querySelectorAll("#x").length==1 ) > > But that limits my browser compatibility. I'd like to support Firefox > < 3.5, which lacks querySelectorAll. Well element.getElementsByTagName('*') gives you alld descendant elements, you could then iterate over that node list and look for an element with the id you are interested in. That should work back to Firefox 1.0 or IE 6 (which you are probably not interested in anyway with using mutation events). Firefox also supports XPath over HTML DOMs so you could also try to solve that with XPath e.g. element.ownerDocument.evaluate('descendant-or-self::*[@id = "' + yourId + '"]', element, null, 9, null).singleNodeValue !== null should tell you whether "element" itself or one of the descendant elements has the id attribute. -- Martin Honnen http://msmvps.com/blogs/martin_honnen/
From: Thomas 'PointedEars' Lahn on 27 May 2010 09:50 Matt Kruse wrote: > Using a document listener on DOMNodeInserted, I'm trying to determine > if an element with id="x" was inserted. So either the > event.target.id=="x" or a child element of the one inserted > has .id=="x". > > What is the best way to determine if #x is a child of the inserted > element? Determine if #x's parent is the inserted element (`parentNode' property). PointedEars -- Danny Goodman's books are out of date and teach practices that are positively harmful for cross-browser scripting. -- Richard Cornford, cljs, <cife6q$253$1$8300dec7(a)news.demon.co.uk> (2004)
From: Matt Kruse on 27 May 2010 10:05 On May 27, 8:50 am, Thomas 'PointedEars' Lahn <PointedE...(a)web.de> wrote: > Matt Kruse wrote: > > What is the best way to determine if #x is a child of the inserted > > element? > Determine if #x's parent is the inserted element (`parentNode' property). I thought of this too, obviously, but it has the drawbacks of: 1. You may have to look through the parentNode chain all the way up to the root document before realizing it's not a match, which seems inefficient 2. If #x already existed in the doc somewhere else, you're going to be inspecting this chain for no good reason It seems that element.getElementById() would be handy in this case, but perhaps performance using any of these methods would be fast enough that trying to optimize is pointless. Matt Kruse
From: Thomas 'PointedEars' Lahn on 27 May 2010 10:10
Matt Kruse wrote: > Thomas 'PointedEars' Lahn wrote: >> Matt Kruse wrote: >> > What is the best way to determine if #x is a child of the inserted >> > element? >> Determine if #x's parent is the inserted element (`parentNode' property). > > I thought of this too, obviously, but it has the drawbacks of: > 1. You may have to look through the parentNode chain all the way up to > the root document You mean root _element_. You may not have to, since not all element types may be descendants of all others. > before realizing it's not a match, which seems inefficient A linked list lookup is certainly not more inefficient than a tree search. > 2. If #x already existed in the doc somewhere else, you're going to be > inspecting this chain for no good reason If #x already existed in the document somewhere else, you have a design problem to solve first. > It seems that element.getElementById() would be handy in this case, It is. BTDT. > but perhaps performance using any of these methods would be fast > enough that trying to optimize is pointless. Perhaps not. PointedEars -- Prototype.js was written by people who don't know javascript for people who don't know javascript. People who don't know javascript are not the best source of advice on designing systems that use javascript. -- Richard Cornford, cljs, <f806at$ail$1$8300dec7(a)news.demon.co.uk> |