javascript collections
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From: Ry Nohryb on 7 Jul 2010 04:26 On Jul 4, 6:42 pm, William Gill <nos...(a)domain.invalid> wrote: > I am working on a snippet and in my research I see that the options > property of the select object is a collection, not an array. I am > having great difficulty finding any good, comprehensive documentation on > javascript collections and their methods. Can anyone point me to a good > reference? > The most important difference between a JS array and a DOM collection is that collections -unlike arrays- are live: var collection= document.getElementsByTagName('div'); var item1= collection[collection.length-1]; document.body.appendChild(document.createElement('div')); var item2= collection[collection.length-1]; item1 === item2 --> false -- Jorge.
From: Ry Nohryb on 7 Jul 2010 04:33 On Jul 7, 10:26 am, Ry Nohryb <jo...(a)jorgechamorro.com> wrote: > On Jul 4, 6:42 pm, William Gill <nos...(a)domain.invalid> wrote: > > > I am working on a snippet and in my research I see that the options > > property of the select object is a collection, not an array. I am > > having great difficulty finding any good, comprehensive documentation on > > javascript collections and their methods. Can anyone point me to a good > > reference? > > The most important difference between a JS array and a DOM collection > is that collections -unlike arrays- are live: > > var collection= document.getElementsByTagName('div'); > var item1= collection[collection.length-1]; > document.body.appendChild(document.createElement('div')); > var item2= collection[collection.length-1]; > > item1 === item2 > --> false Also: var c1= document.getElementsByTagName('div'); var c2= document.getElementsByTagName('div'); c1 === c2 --> true -- Jorge.
From: Richard Cornford on 7 Jul 2010 05:19 On Jul 7, 9:33 am, Ry Nohryb wrote: <snip> > Also: > > var c1= document.getElementsByTagName('div'); > var c2= document.getElementsByTagName('div'); > c1 === c2 > --> true That is extremely unlikely to hold in all environments, and there is no technical reason to expect that it would. It is not a relationship that should be relied upon, probably even in a (semi-)controlled environment such as an Intranet. Richard.
From: William Gill on 7 Jul 2010 11:09 On 7/4/2010 8:27 PM, RobG wrote: >>> I am having >>> great difficulty finding any good, comprehensive documentation on >>> javascript collections and their methods. Can anyone point me to a good >>> reference? >> >> There are not too many properties or methods. >> >> For a start:https://developer.mozilla.org/En/DOM/NodeList > > The definitive reference is the W3C DOM Core spec, the above page has > a link to the DOM 3 Core reference, which doesn't seem to have changed > since Level 1. > > However, the OP was asking about collections, which are a type of > NodeList that have some extra features: > > DOM 2 HTMLCollection > <URL: http://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-75708506> > > DOM 2 introduced the HTMLOptionsCollection interface, which is similar > to other collections but differs in that the namedItem method accepts > only an id and that length is not readonly, so it can be used to set > the number of items (e.g. as a quick way to remove all options, set > length to zero): > > DOM 2 HTMLOptionsCollection > <URL: http://www.w3.org/TR/DOM-Level-2-HTML/html.html#HTMLOptionsCollection >> > > The relevant HTML5 reference is: > <URL: http://www.w3.org/TR/html5/common-dom-interfaces.html#collections-0 >> > Thanks Rob, and everyone. Good starting point. The DOM core refs I have, though searchable (pdf) didn't help too much.
From: Garrett Smith on 7 Jul 2010 20:56
On 2010-07-06 11:25 PM, RobG wrote: > On Jul 7, 9:48 am, Garrett Smith<dhtmlkitc...(a)gmail.com> wrote: >> On 2010-07-06 09:41 AM, Dr J R Stockton wrote: [...] >> "1.3 How can I post to comp.lang.javascript" >> >> It is best to post through a newsreader, such as Thunderbird. > > I have a mostly hate relationship with Thunderbird. It's newsgroup > filtering leaves a lot to be desired - why can't I run a filter on > messages that have already arrived? > > Anyhow, I find it pretty useless as a news reader and there aren't any > others worth using on Mac OS. Perhaps I'll switch to a Windows-based > agent. > OK, TB's at least better than GG I hope. What other readers are worth recommending? Would a list of two or three be right for the FAQ? -- Garrett |