i'm using DD_Belated.png to save all IE6 users from seeing the madness of unsupported png.
However, this great script takes either selector or DOM Element as parameter to it's only function to do it's magic and return working PNG to IE6.
Me, being lazy programmer, did something like this:
$("img[src$=png], #search").each (
function() {
DD_belatedPNG.fix( *what-here* );
});
SO, basically I need some jQuery function to return DOM Element from $(this).
BTW, neither $(this).get(), $(this).get(0) nor $(this)[0] does work in IE6
Thank you.
Edit: Once again, the problem was between monitor and seat - in me. There are two methods - one for selector string and one for DOM Element. I used the first one for both - and I thought I'm not passing good argument with this, so I began to look into different - well, I did not gave the right argument - It expected string...
In your .each function, the "this" variable will be your DOM element. Thus:
DD_belatedPNG.fix(this);
should do it.
I'll add, sadly, that I've never gotten any IE6 PNG fixers to work, at least not really work.
did you try DD_belatedPNG.fix(this);
Related
I have searched prior SO posts here, here and here, and couldn't an answer that made sense to me. This should be a basic question, but I'm not understanding the posts I find. They don't seem to address using a this parameter.
I want to programatically add an input with an onchange event, such that the final result is this:
<input type="button" onchange="handleButtonOnChange(this)">ClickMe</input>
I am working on a project that is using an embedded IE6 browser inside a old Delphi application, so I have to have a solution that is IE6 compatible (yes, IE6 is horrible, but there are reasons I am stuck with it for now).
My initial attempt was this:
var DaySelect = document.createElement("select");
DaySelect.id = ParentID+"-day";
DaySelect.disabled = true;
MonthSelect.onchange="handleDayChange(this);" //<--- not correct
Parent.appendChild(DaySelect);
I then read that the .onchange should be assigned an object, not a string, and one should use this instead:
MonthSelect.onchange=handleDayChange; //<--- '(this)' removed
But it seem to me that this will result in this element (notice the missing this parameter)
<input type="button" onchange="handleButtonOnChange">ClickMe</input>
If I use the line below, instead, won't this make a closure, and the 'this' will refer to the event at the time the object is assigned to the .onchange property, instead of being the event at the time of the change event?
//Does the line below make a closure?
MonthSelect.onchange=handleDayChange(this); //<-- What does 'this' refer to?
I'm a relatively new web programmer, but long time Delphi programmer. Closures still make my head hurt. I appreciate any help in this.
Also, I read here about using addEventListener and the problems with older versions of IE, and the last post on the page provides a work around. But I don't understand how it works.
EDIT -- And what about passing other parameters? It seems that many event handlers will need to have parameters specific for the attached element. It seems that it is just not possible to add a listener with any parameters.
A simple closure if you are creating the elements in JS as you show:
var DaySelect = document.createElement("select");
DaySelect.id = ParentID+"-day";
DaySelect.disabled = true;
MonthSelect.onchange=function(){handleDayChange(DaySelect);};
Parent.appendChild(DaySelect);
Since the function is created inside the scope that you create the element in, the same variables will be available to it.
EDIT:
Additional parameters can be passed with this method, for example, the anonymous function we create and attach as the handler will still have the event object sent to it:
function(e){handleDayChange(DaySelect, e);};
In the event object you will have access to the event target, but in your example the event target and "this" are not the same element, so there would be no way for the handler to know about the DaySelect element.
jQuery makes a lot of event handling much simpler which is one of the reasons many people use it, it also normalizes it's methods between various browsers so you don't have to write multiple versions of the same code (in most cases)
Hello this seems to be working on IE8 :
var clsName = link.parents("div.fixed_column").attr("class").split(" ");
if($.inArray("column_one", clsName)
While this one reports error (Object expected errror in jquery).
var clsName = link.parents("div.fixed_column").attr("class");
What is the right way to do this? I thought purpose of inArray was that jquery will handle cross browser issues.
Unfortunately, this is indirectly answering your question, but... You seem to be looking to detect if an element has a class, and since you're already using jQuery, just use the hasClass method - http://api.jquery.com/hasClass/
For your specific code, try:
if (link.parents("div.fixed_column").hasClass("column_one")) {
// It has the "column_one" class
}
The more immediate answer to your question is that link.parents("div.fixed_column").attr("class") returns a single string. When the jQuery selector (div.fixed_column) returns multiple elements, which is very possible when using classes, using jQuery methods that get information (like .attr, using one parameter...to "get" the value) return the first matched element's value only.
So say the selector matches 3 elements:
["<div id='div30' class='fixed_column div30_class'></div>",
"<div id='div2' class='fixed_column div2_class'></div>",
"<div id='div17' class='fixed_column div17_class'></div>"]
Then the value returned from .attr("class") will be: fixed_column div30_class because it's the first matched element.
I'm not sure, but I think you're expecting jQuery to return an array of all the matched elements' values, which it just doesn't. So that doesn't mean jQuery isn't handling cross-browser issues, it just means you need to look up what the method does/returns.
I could've sworn that jQuery 2.0 has options for doing what you want - directly from calling the getters (or something similar), but I can't find it anymore :( Maybe I'm remembering incorrectly. Anyways, you could easily use $.each and/or $.map to look at every matched element, but it depends on what you were really trying to do with it.
You can't read the attributes of multiple elements into an array with .attr("class"). But why don't you just target the desired class in the selector like this?
var cols = link.parents("div.fixed_column.column_one");
Then change your conditional to check for an empty set:
if(cols.length) { ...
Here is the code block a
$('ul.filter li').each(function() {
$(this).click(function(e) { //do something });
});
Here is code block b
$('ul.filter li').click(function(e) { //do something });
Don't these do the same thing? is one better than the other? Which one is the better/faster method?
I would assume block b since it has less code but I want to confirm it here, thanks
The effect you see will be the same, but in the first case, every li element is assigned a new function, as you are creating the function object inside the each callback.
In the second case, there exists only one copy of the event handler, which means it uses less memory over all (although this is probably not measurable).
Internally, click calls on (in jQuery 1.7), which is iterating over the elements via each as well:
return this.each( function() {
jQuery.event.add( this, types, fn, data, selector );
});
This is the case with many jQuery methods (most often noted in the documentation), so you are saving characters and memory by letting jQuery implicitly do this.
They would both have the same effect.
I would prefer the second only because it is more concise and you're creating a single anonymous function to handle the click rather than an anonymous function per element.
For Jquery philosophy, the second is better because it is shorter.
Both are more or less same and give the same results. The second code snippet will also internally run each loop and assign the click handler to each li element.
But yes the second code snippet is very clear and simple.
The second usage is called "implicit iteration" and is one of the cornerstones of jQuery.
For example, in JavaScript Definitive Guide, 6th Ed, p.530 for jQuery Basics:
Despite the power of the each() method, it is not very commonly used,
since jQuery methods usually iterate implicitly over the set of
matched elements and operate on them all. You typically only need to
use each() if you need to manipulate the matched elements in
different ways. Even then, you may not need to call each(), since a
number of jQuery methods allow you to pass a callback function.
in http://jqfundamentals.com/chapter/jquery-basics
Implicit iteration means that jQuery automatically iterates over all
the elements in a selection when you call a setter method on that
selection. This means that, when you want to do something to all of
the elements in a selection, you don't have to call a setter method on
every item in your selection — you just call the method on the
selection itself, and jQuery iterates over the elements for you.
Typically, when the library has this built-in as the standard way of doing it, it will be in general better and faster, or else they wouldn't have built it in.
function eegetdropdownvalue_str(ctl){return ctl.selectedIndex>=0&&ctl[ctl.selectedIndex]?ctl[ctl.selectedIndex].value:''}
The above function is called with
co.p1A10=eegetdropdownvalue_str(document.formc.p1A10);
I want to switch the call over to jQuery to drop the document.form reference however doing this
co.p1A10=eegetdropdownvalue_str($('p1A10'));
Does not reference the control correctly - How should I do this?
There's two things wrong with your code.
First, $('p1A10') references nothing.
jQuery selectors work almost identically (if not completely identically) to the way css works.
So, just ask yourself how you would reference the object(s) in question in CSS and you're half way there.
I'm assuming that p1A10 is the name or id of an object. Since we're using CSS/jQuery syntax, this should be an id, although you can select by other attributes such as $("select[name='p1A10']") .
To reference an object by ID we use the # character (again, just like in CSS). So we can select your node via $('#p1A10').
The second problem is that your function is expecting a DOM object not a jQuery object. To keep your code intact, we need to say $('#p1A10')[0] where 0 is the first element within the collection of jQuery elements.
I've provided two examples to explain this a little better. One uses your existing infrastructure and one replaces it.
http://jsfiddle.net/TD6Uu/5/
Hope it helps.
Given a form with id formc and a select with name p1A10 you could e.g. use:
o.p1A10 = eegetdropdownvalue_str($('#formc select[name="p1A10"]').get(0));
If this doesn't do it, please provide use with the exact HTML structure
I am getting the following error in IE:
'events' is null or not an object -- jquery-latest.js?d=1848173663, line 113 character 467
I am using jQuery 1.4.2, I'm not in a position to upgrade yet as we are on an older version of jQuery UI and have way too many bugs using anything newer than 1.4.2.
I get following error when I run this bit of code the second time:
$.post("page/view.do?undoCache=" + Math.random(), {
pageId: pId
}, function(xmlContent){
console.log('1');//get this one
$('#reloadCenterDiv').empty();
console.log('2');//don't get this one unless line above is commented out, then will run til next line
$('#reloadCenterDiv').html(xmlContent);
console.log('3');//don't get this
});
I'm pretty sure I'm not doing anything else to #reloadCenterDiv between calls.
Googling around for the error "'events' is null or not an object" I found this:
"Sounds like a reference to an event
handler is still there, when the
handler itself is already gone."
That sounds logical. Any other ideas of why and when this error would occur?
I have found where this is happening, but all clues for me end there.
How do I clean things up so I can call empty() or html() on #reloadCenterDiv again?
Here is the HTML for #reloadCenterDiv:
<div id="reloadCenterDiv" style="border:none; margin: 0; overflow:auto; overflow-y:scroll; height: auto;"></div>
Not sure, but it would seem like jQuery.cache is being overwritten.
Since a DOM element has (when necessary) a serial number that maps to jQuery.cache, when you run a function like .empty(), jQuery assumes the related data exists, looks up the data for that element, and deletes it.
In place of your first log, do this:
console.log(jQuery.cache);
And see what it gives you. I'll bet that something is overwriting it. Perhaps you're loading jQuery twice?
Here's an example that intentionally deletes jQuery.cache. It gives a similar error.
EDIT:
Summary of the comments below. During .empty() (or actually cleanData()) jQuery grabs the expando from all descendant elements in order to delete the associated data.
The issue is that when jQuery does so, it assumes that the data was successfully located. In this case, somehow the data is being disassociated from the element, so retrieving the data using the value of the expando is returning undefined.
Because jQuery doesn't (or didn't in 1.4.2) verify that data was found, its attempt to access the events property on the data is causing an error, because again data is undefined.
Updated versions of jQuery fix it with if ( data && data.events ) {, which verifies that there is some object against which to ask for its events property.
If you can't update your jQuery, you can set the HTML instead:
$("#divid").html("");
This is essentially doing the same thing.