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- Screen name: ray.bellis
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- 10-Mar-2013 07:37 AM
- Forum: Developing jQuery Core
In an answer to a Stack Overflow question I enumerated all the ways I knew to get the "first children" of a jQuery object.I had originally suggested that .children().first() wouldn't be very efficient because it requires jQuery to first build the list of all children, and then create a new jQuery object that only contains the first element.So I wrote a plugin which uses .firstElementChild if available or iterates over the children directly otherwise. In the former case the plugin effectively becomes:- $.fn.firstChild = function() {
- return this.map(function() {
- return this.firstElementChild;
- });
- };
Curiously, I've found via jsperf that on Chrome 25 this is actually slightly slower than .children().first() although it's 50% - 130% faster in Firefox and Safari.The real question is why is $(body).firstChild() from my plugin still 15x slower than just $(body.firstElementChild)? The latter is incredibly fast, but not portable. What is it about the chaining here that completely kills the performance?- Has anyone else noticed a degradation in the performance of draggables (i.e. Dialog boxes) since Chrome 18?Dragging a dialog around now feels very laggy on my MacPro, although with the latest Safari it still feels very snappy.
- 26-Jan-2012 05:39 AM
- Forum: Developing jQuery Core
Whilst trying to answer http://stackoverflow.com/q/9016200/6782 I found that it appears impossible to select text nodes using .nextAll(), .nextUntil() etcThese functions currently _only_ return HTMLElement nodes, as do .children(), .siblings(), etc. The only function that can obtain text nodes is .contents().AFAIK the only jQuery traversal function which accepts a function in place of a selector is .filter() itself.It might be very useful if all those traversal functions that allow a "filter selector" also permitted an explicit filter function, and when supplied then consider _all_ nodes, and not just HTMLElements.- 20-Jul-2011 11:42 AM
- Forum: Using jQuery UI
I've just discovered that if I specify a callback handler in the constructor of a jQuery UI widget (or pass it as an option), e.g.- $dlg.dialog('option', 'resize', ...)
it's not the same as:- $dlg.bind('dialogresize', ...)
because in the former case I can't invoke the callback by calling- $dlg.trigger('dialogresize')
Is this difference intentional? I can't see it documented anywhere.- 29-Jun-2011 10:58 AM
- Forum: Developing jQuery Core
Whilst debugging some third party code that was no longer working under 1.6.1, we discovered that this code:- var id = $el.attr('id');
where $el has no id attribute would return an empty string under 1.5.2, but now returns undefined.Is this apparent change documented anywhere? It's not explicitly mentioned as far as I can see in the 1.6.x release notes.It looks like maybe this is because the old pre 1.6 code would fall through on the undefined attribute to the always-existing-but-empty property value.- 04-May-2011 04:26 AM
- Forum: Developing jQuery Core
Just wondering - is there any particular reason why $.ajax() ".complete()" method isn't implemented using deferred's new ".always()" method?Ray- 17-Mar-2011 06:46 PM
- Forum: Using jQuery
In this question on Stackoverflow, I suggested use of $.Deferred()
My original fiddle for a solution used a separate callback function which just called def.resolve().
However I then remembered that I've seen other code simply pass "def.resolve" as a callback in its own right. I tried this instead, and it works (see http://jsfiddle.net/Nyg4y/3/).
This got me wondering - how does this work? As I understand it for this to work at all the value 'def.resolve' must be specific to 'def'.
This suggests that it is actually a (reference to a) closure holding a reference to 'def' in its scope. Is my understanding correct, and if so is this behaviour guaranteed?- I noticed that the Date Picker stores a global ("DP_jQuery" + dpuuid) for conflict avoidance even if no widget is ever created.Whilst it would be better not to have it at all, couldn't it be at least deferred until the first time a date picker is instantiated?
- 09-Mar-2011 07:00 AM
- Forum: Developing jQuery UI
In our application we've noticed that hovering over the 'x' close button dialog box causes the browser status to show '.../path/#' in the status bar, or in Chrome make that appear as a popup in the bottom left.When adding extra buttons to the title bar I've used a <div> instead of <a href="#"> and then added this to our CSS to make sure we get the right cursor.- *[role="button"] {
- cursor: pointer;
- cursor: hand;
- }
Is there any particular reason (accessibility?) why the current code uses that <A> tag?- «Prev
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