I have an anchor tag in my application that has the sole purpose of firing some javascript to expand/collapse some panels. I was thinking about changing it to be a span with a click handler instead. Which is the best method:
<a href="javascript:togglePanels()">Toggle Panels</a> OR
<a onclick="togglePanels()" href="javascript:void(0);">Toggle Panels</a> OR
<span onclick="togglePanels()">Toggle Panels</span> Or is there a better option that I have not included?
I would use a <button>. You can style it accordingly with CSS, but the semantic meaning is still preserved.
But if the user disables JavaScript, the button becomes useless and users might get confused.
If your site works with JavaScript only anyway, then this would be ok, but if it also works without, you better add it programmatically or hide it initially with CSS.
Update:
Don't forget to set type="button". By default a button is a submit button for a form, so omitting the type attribute would make it some kind of invalid outside of a form (although it would still work).
A common progressive-enhancement approach is to make your anchor an actual anchor link... if JS is not available, clicking the link will just bring the panels (which you can place down below, in the flow of the document, and hide on dom-ready/load when JS is available) to the top.
<a href="#panels" id="panelToggler">Toggle Panels</a> <div id="panels"><!-- your panels--></div> Then in your click handler for #panelToggler, first use e.preventDefault() so it won't try to pull the anchor to the top, then include the logic to toggle the panels.
If you don't care about users without JS being able to use whatever is in the panels, then don't even show them the toggle panels control at all. Even if it doesn't look like a link, it is really janky to just have a non-working "toggle panels" line of text sitting there in your UI. In this case, it really doesn't much matter what element you hang the functionality on for the JS-enabled users... button is appropriate, but a is generally more flexible with styling options. Take a look at most of the buttons in GMail... they're clusters of nested divs.
I prefer to define a span element without any handler attributes, and then wire up any handlers in a separate script file. In my case, I have many different span elements with the same toggle expansion behavior, so giving them all the same class, like "expand", allows me to wire them all in my document loaded method using a class selector.
The better option would be using unobtrusive JavaScript:
var element = document.getElementById("#anchorId"); element.onclick = togglePanels; A jQuery approach also helps a lot:
$("a").click(togglePanels); But of course I think that it's nice as an anchor, since you can still have an href pointing to something in case the user isn't with JavaScript enabled.
onclick inside the HTML is one of the thing that directly goes against to the unobtrusive approach.Yes, if the element is in your original markup, the span is better. This is in the interest of some semblance of graceful degradation; users who don't have JavaScript enabled will still get the impression they can interact with the hyperlink, which they cannot.
The truly idealized unobtrusive solution would be to not include the element in the markup at all, and add it programmatically using JavaScript.
At the very least, you should not use the javascript: protocol in a hyperlink reference. Aside from challenges some might make that it is an improper use of hypertext references (hyperlinks should reference documents or resources, not define behavior) it poses a few technical challenges; for example, you don't have access to the anchor element via this.
I learned that a anchor will make the browser "ready to launch" when focused. Meaning some resurses will used. But I think transparency is important: http://www.javascripttoolbox.com/bestpractices/#onclick
Mike
