Difference Between Empty Attribute And Undefined Attribute
Apr 24, 2007
I'll trying to tell the difference between the following three cases:
<img alt="text string" />
<img alt="" />
<img />
I can do this in Firefox with the following code, where elem is the
HTMLElement representing each image, but IE doesn't seem to
differentiate between empty string and undefined.
var alt = elem.getAttribute('alt');
alt = (alt) ? alt : ((alt===null) ? 'really_null' : "");
The desired output from running this code on the 3 tags above is:
text string
really_null
It seems like this should be really easy...but I'm having a really
difficult time trying to figure out what's going on...
i have found a possible bug in 1.4 but it's only in Internet Explorer 7 & 8.The following code does not work and completely ruins every peice of jquery on the page (that means everything inside $(document).ready and anyting else...
I cant see any syntax errors - i pulled the example from the 1.4 site. There is no trailing commas in the object notation and i really cant see any reason it would work in firefox and not IEx and more to the point not only not work in IEx but break any other jquery in the entire page....
I'm working with a large (and unweildy) ASP.NET application, and there is a lot of jQuery code that uses selectors like this:
[name=_aspnetControl$_withASubControl] And unfortunately, some selectors that also look like this:
[name^=_someAspNetControl$_radioButtonList].
In other words, the effort to remove the $ from the attribute selectors would be monumental. If it is possible to escape the $ symbols, I can do that easily enough, but unfortunately the situation right now means that I can't upgrade to jQuery 1.5.
I'm learning jQuery with XML. I'm familiar with other query languages such as XPath. I'm having a little bit of difficulty wrapping my brain around how jQuery works but I think I can make the leap if I see a solution to a problem I know how to solve with other methods Given the following XML, please share a jQuery solution to finding the value of attribute B in elements named bar where attribute A has the value 30:
I was wondering if someone could help me here. I need to set the class attribute of an HTML element to a specific value using javascript, can someone give me an example of how I might do this as the syntax
I'm loading an XML document and grabbing a node with content in it including html. I can't figure out how to grab the src of the first IMG tag that appears in this text string
I am aiming to change a couple of items on a CSS definition using JavaScript, so the servicer only needs to update one JS variable. I am so a novice at this...
I would like to be able to set the "top" and "height" attributes of my graphbar ID element after the percent in the JS script is changed.
I'm trying to get the value of an object's property. getAttribute returns "null" even though I'm sure the property is set. I can easily set the property, and in my actual script I do so dynamically. I just want to read the property and can't.
To help explain my problem, I've attached an example .html file as a .txt file.
The critical part of the code is this section that is based on "textbook" examples of how to get an attribute:
<script type="text/javascript"> function showcolor() { var myobject = document.getElementById("lab"); var myproperty = myobject.getAttribute("color");
alert(myproperty); } </script>
This is called via a button on the bottom of the page. The DIV object with the ID "lab" exists and has a color attribute defined in CSS, but I cannot read it, nor any other attribute, with a script. The alert displays "null".
I've been working on a dynamic script using the DOM and wanted a routine that would parse out the element attribute collection. I came up with a routine that works in FireFox 1.5 and Opera 8, but it doesn't work in IE 6. Any ideas? Code:
Im trying to make a script which when I click on the list element... it will replace a big image with anotehr picture. The list element is a thumbnail... and I want to swop the big image with the big version of the thumbnail. Each <li> has a rel attribute... but while I can pull out each <li> from the list, for some reason the following code, yields an 'undefined' value... instead of the big-image-path...?
I'm trying to create a text-only version of one of my sites. I have a toggle link switching between text and full html versions. If text-only was selected, then it changes the stylesheet.However, I need to be able to replace all <img> tags with their associated alt attributes to make it completely text-only.
Does anyone know exactly what the defer attribute for the script tag is? I read that it tells the browser to load the page first (once the body tag is fully loaded) and then load the contained <script>.
If so then how does it cope with cached scripts? Say for example a <script> has already been loaded then the page is accessed again, will the <script> contents be executed right away since the contents do not have to be downloaded?
Also, if you do not have a src attribute (the contents are on the page and not in a separate file) then does the defer attribute really do anything?
I am aware that it's in the HTML specification and that it's not a MSonly thing. But this is the first time I've ever seen the defer attribute, so I don't think it's really mainstream. All of my scripts that load up when the page is loaded are triggered by window.onload and since lately I use mootools, then they are loaded after window.onDomReady.
