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Ajax is the new web 2.0 fad, and it is probably here to stay for quite some time. AJAX, or Asynchronous Javascript and XML, is a method used to communicate with the server and load new content in a website without having to reload the page. You’ve probably seen it all over the web, but possibly without necessarily thinking about what it is. The minor difference makes a huge positive impact on users, and a pretty negative impact on page impressions.

So what type of things would AJAX come in handy for? Well a very common implementation is for search tools. Say you are on a site looking for houses and there are tons of criteria you can enter in to narrow down your search. It is really helpful to see how each change in your criteria affects your results. To offer constant feedback, web developers need to use AJAX to bring back search results each time you change criteria. If they didn’t use AJAX, you’d be staring at a page reload every time, and that’d be mindbogglingly annoying…

A great example is a search tool I worked on at my company, College Prowler. The tool is meant for high school students trying to find colleges that fit their criteria of where they want to attend a college. Test it out and see for yourself <a href=”http://collegeprowler.com/finder/” target=”_blank”>here</a>. The telltale sign of AJAX by the way is one of those circling gifs to indicate something is loading, so keep an eye out for that as you browse the web.

So now maybe you understand the benefits of AJAX. It makes for a much more fun and usable experience for users as they traverse your website. The serious downside is a decrease in your pageviews. Every time you make an AJAX call, you lose what would have been a new page load and thus a new pageview. With each pageview (if you know what’s good for you AND have a highly trafficked website), you gain ad income. Now you could argue that with the improved user experience, you’ll make up for the lost pageviews in your AJAX tool with more devoted users (an argument I agree with), but that doesn’t cut it for everyone.

So make the choice to go with AJAX. In an upcoming post, I’ll write about the basics of AJAX and how to implement it.
Cheerio!

Up until recently I’d never implemented a rollover dropdown menu. Then I just decided to build one from scratch for my employer College Prowler to improve upper-level navigation. Basically, with some simple javascript to hide/show the menu and some CSS to style and position it, you’ve got yourself a simple javascript rollover dropdown menu! The code follows the example implementation below.

The Javascript:

function rolloverMenu(showHide, menu)
{
    var link = 'mainLink';
    if (showHide == 0)
    {
        document.getElementById(menu).style.display = 'none';
        document.getElementById(link).setAttribute('class', 'mainNav');
        document.getElementById(link).setAttribute('className', 'mainNav');
    }
    else
    {
        document.getElementById(menu).style.display = 'block';
        document.getElementById(link).setAttribute('class', 'selectedRollover');
        document.getElementById(link).setAttribute('className', 'selectedRollover');
    }
}

This javascript will either hide or show the menu depending on the location of the cursor. The HTML that calls the javascript has a delay on it as well, but you’ll see that later. This javascript also changes the class name of the link so that even though your mouse isn’t technically hovering over that link it will look like it is being hovered over.

The CSS:

#container{
    position: absolute;
    z-index: 1001;
}
a.mainNav{
    color: White;
    font-weight: bold;
    font-size: 12px;
    height: 40px;
    padding: 0px 10px;
    line-height: 40px;
    float: left;
    background-color: #1D3E66;
}
a.mainNav:hover{
    background-color: #3D6199;
    color: #AAAAAA;
}
a.selectedRollover{
    color: White;
    font-weight: bold;
    font-size: 12px;
    height: 40px;
    padding: 0px 10px;
    line-height: 40px;
    float: left;
    background-color: #3D6199;
}
.rolloverMenu{
    float:left;
    padding: 10px 10px 6px 10px;
    position: absolute;
    z-index: 1000;
    background-color: #3D6199;
    width: 100px;
}
.rolloverMenu#mainMenu{
    top: 40px;
}
.rolloverMenu a{
    color: White;
    font-weight: bold;
    font-size: 12px;
    line-height: 20px;
}

Change the CSS to fit your own design. I’ve been very specific in this CSS so that it should be easier for you to identify everything. Note that the #container definition is actually very important for an IE6 bug fix. IE6 has issues with z-index when not combined with absolute positioning. Basically, the parent element of the rollover menu needs to have that specific definition.

Lastly, the HTML:

<div id="container">
   <a class="mainNav" href="#" id="mainLink"
      onmouseover="rolloverMenu(1, 'mainMenu');"
      onmouseout="rolloverMenu(0, 'mainMenu');">
         College Search
   </a>
   <div class="rolloverMenu" id="mainMenu" style="display: none;"
      onmouseover="rolloverMenu(1, 'mainMenu');"
      onmouseout="rolloverMenu(0, 'mainMenu');">
         <a href="#">Link 1</a><br />
         <a href="#">Link 2</a><br />
         <a href="#">Link 3</a><br />
         <a href="#">Link 4</a>
   </div>
</div>

And that’s that! The HTML link calls the javascript which implements a series of CSS rules that will hide or show the menu of your choice! Have fun!

Well, this is my last javascript post for a bit, seeing as this is just an offshoot of my last post Javascript: Dynamically Altering CSS Properties. In this post, we’ll go over creating a simple Javascript watermark for a textbox. A textbox watermark can help encourage its use and reduce confusion for your users. I typically employ a watermark for textboxes that exist outside of a form (they only gather one piece of needed information such as a zip code as opposed to an entire address).

So either in an external Javascript file (which is called the same way as an external CSS file), or in the head of your HTML inside a <script> tag, include the following javascript:

The Javascript:

function hideWatermark(theID)
{
    var element = document.getElementById(theID);
    element.style.backgroundImage = 'none';
    element.style.backgroundColor = 'white';
}
function showWatermark(theID)
{
    var element = document.getElementById(theID);
    if (element.value.length == 0)
        element.style.backgroundImage = 'url(\'IMAGE_LOCATION_HERE\')';
    else
        element.style.backgroundColor = 'white';
}

On focus (when the user clicks on the textbox) the hideWatermark function is called. The javascript takes in a string of the textbox ID. It then sets the background image to none, and the background color to white. On blur (when the user clicks away from the textbox, putting focus on any other element), the showWatermark function is called. This javascript also takes in the same ID. It then checks to see if the content of the textbox is empty, if it is, it puts the background image of the watermark back in. If it is not empty, then it keeps the background color as white.

Here is the HTML that goes with the JS:

<input type="text" class="gatherZip" id="theTextBox"
   onblur="showWatermark('theTextBox')" onfocus="hideWatermark('theTextBox')" />

And the CSS:

.gatherZip{
   background: white url('IMAGE_LOCATION_HERE') no-repeat center center;
}

The image you create can say or imply whatever you want. As an estimate, try to keep the image no more than about 15 pixels high or it won’t fit in standard sized textboxes. And that’s it. A beautiful textbox watermark just for you and your users! Comments? Questions?

I’ve been on a string of javascript posts, starting with Javascript: Opportunities Abound and then Javascript: Changing Class Names to Alter CSS. Well now I want to talk about a variant of altering CSS classes, and that is just altering inline style. I use this infinitely more than changing a CSS class. You can do a lot of very easy and simple interactions for the user that are really quite easy. You can show and hide divs, change background colors or images (I’ll use that to create textbox watermarks in my next post), and much more.

So either in an external Javascript file (which is called the same way as an external CSS file), or in the head of your HTML inside a <script> tag, include the following javascript:

The Javascript:

function changeInlineStyle(tagID){
   var theTag = document.getElementById(tagID);
   if (theTag.style.display == 'block')
      theTag.style.display = 'none';
   else
      theTag.style.display = 'block';
}

The javascript first takes in a string with the tag ID that you send to it in the HTML below. Then, it creates an object that represents that ID which is named theTag. Then with a simple if statement, the javascript checks to see if the object is visible. If it is, it hides it, if it is hidden, it shows it. This is great for toggling a div with certain content. You can change different aspects of style though. Try "backgroundImage" or "backgroundColor" to change background characteristics. You can mess around with any aspect of tag’s style that you want. Text color, float, width, height, whatever you want. I have found the most common ones I use are display, backgroundColor, and backgroundImage though.

Here is the HTML that goes with the JS:

<a href="#" onclick="changeInlineStyle(targetTag);">
<div id="targetTag">This div will hide when the link above is clicked</div>

Yep, simple as that! When the link is clicked, it calls the javascript function, sending over the id to identify the tag it should work with. In this case, the link targets the div below it. Simple as that! I’ll talk about textbox watermarks next. Comments? Questions?

As I discussed in my previous post, Javascript: Opportunities Abound, javascript is very powerful and can be used for a wide variety of client-side interactions. One of the most useful items I’ve found for it so far (mostly because of how much I love CSS) is to alter CSS classes! And the best part is it is incredibly easy. So either in an external Javascript file (which is called the same way as an external CSS file), or in the head of your HTML inside a <script> tag, include the following javascript:

The Javascript:

function changeCSS(tagID)
{
   var currentTag = document.getElementById(tagID);
   currentTag.setAttribute("class", "secondClass");
   currentTag.setAttribute("className", "secondClass");
   return;
}

The second setAttribute function is for certain versions of IE that for some odd reason (IE sucks) setting the class through javascript does not always function properly. I personally have not noticed this issue with IE6 or IE7, and IE5 is tops 1% of your users, so you can probably leave it out, I’ve just seen other people using it…

And now the HTML that goes with that JS:

Yep, simple as that! When the link is clicked, it calls the javascript function, sending over the id to identify the tag it should work with. In this case, the link is adjusting it’s own CSS, but it can work on anything else in the page. But what if you want the link to work both ways, to be able to change the CSS class of an object back and forth instead of just one direction? Try this on for size, a simple if statement in your JS function (the same HTML will do)

The New Javascript:

function changeCSS(tagID)
{
   var currentTag = document.getElementById(tagID);
   if (currentTag.className == "firstClass")
   {
      currentTag.setAttribute("class", "secondClass");
      currentTag.setAttribute("className", "secondClass");
   }
   else
   {
      currentTag.setAttribute("class", "firstClass");
      currentTag.setAttribute("className", "firstClass");
   }
   return;
}

And that’s that! Simple right? It is also possible to just change a specific aspect of the CSS instead of the entire class, but I’ll talk about that in a future post. Comments? Questions?