Tag: jquery

Using getResponseHeader with jQuery’s ajax method

The Canvas API uses pagination for requests that return multiple items. The URL of the next result set is specified in an HTTP response header. I know how to get the response body, but how do I get the response headers from a jQuery AJAX call?

The jQuery ajax documentation indicates that the “[jqXHR] object returned by $.ajax() as of jQuery 1.5 is a superset of the browser’s native XMLHttpRequest object.” And the XMLHttpRequest object includes a getResponseHeader method.

At first I tried calling getResponseHeader as a method of the data object:

$.ajax({
    url:'/api/v1/courses'
}).done(function (data) {
    console.log(data.getResponseHeader('Link'));
});

But data contained just the response body, and data.getResponseHeader was null.

A closer look at the jQuery documentation indicated that additional objects are passed to the done function, including the jqXHR object. Accessing that object’s getResponseHeader method worked:

$.ajax({
    url:'/api/v1/courses'
}).done(function (data, textStatus, xhr) { 
    console.log(xhr.getResponseHeader('Link')); 
});

More People Alive Today Than Have Ever Died

A few years ago, I ran across this quote:
“There are more people alive today than have ever died.”

As we contemplate overpopulation, a quote like that is quite thought-provoking and shocking. Could it be that the living today outnumber all of our ancestors? It’s astounding. However, I didn’t believe it. I still don’t believe it, and for good reason.
Continue reading More People Alive Today Than Have Ever Died

jQuery is AWESOME

I just took (and finished) a small project to add some ajax and javascript whiz-bang to a website. (actually it was the home page for a web development company you would think that they would keep that in house) and I decided to try out jQuery.

It blew my socks off. I’m really really impressed with jQuery, and I’m looking forward to using it a lot more. It took me an hour or two to really get a handle on how a few parts of it work, but man is it a powerhouse. If your website needs to sing and dance…. jQuery is the way!

Javascript textarea counter

I’ve been thinking more about the textarea counter issue that I mentioned in my previous post (“Users Paste Differently“).

First of all, I noticed that some of the textarea counter scripts date back to at least 2000, so this has been a problem that developers have been looking to solve for 8 years. I checked the HTML 5 specification and found that in HTML 5, the textarea element has a maxlength attribute. Presumably user agents will build in the most elegant solution.

But what is the current most elegant solution? Continue reading Javascript textarea counter

The Javascript Dollar Sign ($) Function

Recently, I’ve been seeing a lot of Javascript functions prefixed with a dollar sign ($) or simply named $. I thought, what sort of magical property does the dollar sign have in Javascript? What sort of esotericism had I uncovered?

The Dollar Sign Magician

I checked the O’Reilly Rhinoceros book, and found that the dollar sign has no special properties.

However, I have come to discover that dollar sign function has become the more-or-less de facto shortcut to document.getElementById(). Let’s face it, we all use document.getElementById() a lot. Not only does it take time to type, but it adds bytes to your code as well.

Here’s the version from prototype.js, which can return more than just a single element:

function $(element) {
  if (arguments.length > 1) {
    for (var i = 0, elements = [], length = arguments.length; i < length; i++)
      elements.push($(arguments[i]));
    return elements;
  }
  if (Object.isString(element))
    element = document.getElementById(element);
  return Element.extend(element);
}


Because it has become a common shortcut to document.getElementById(), it means that various Javascript libraries should play nicely together: if the dollar sign function in one .js file is overwritten by the same dollar sign function in another .js file, everything should still work. That also means that creating your own dollar sign function that does something different is probably not a good idea.


In case you were wondering, the underscore has no special properties either. But let’s face it, $(‘myVal’) looks more like programming than _(‘myVal’).


Update 2012

By now, the most common use of the $() function is as synonym for jQuery() in the popular jQuery Javascript framework. It returns a jQuery object (or objects), which includes much more than just a reference to the DOM element. (In jQuery, you can still access the underlying DOM element using .get().)


Likewise, the Prototype code I cited above also returns more than just a reference to a DOM element, as it returns an extended version of the element. As such, Prototype and jQuery will almost certainly not work well together in the majority of cases.