atb-ajax

This is a plugin that Eldarion uses for all of its AJAX work.

No more writing the same 20 line $.ajax blocks of Javascript over and over again for each snippet of AJAX that you want to support. Easily extend support on the server side code for this by adding a top-level attribute to the JSON you are already returning called "html" that is the rendered content. Unlike a backbone.js approach to building a web app, eldarion-ajax leverages server side template rendering engines to render and return HTML fragments.

This project used to be called bootstrap-ajax but the connection with Twitter Bootstrap was tenuous at best so we thought it best to rename to eldarion-ajax.

Demo

There is a demo project at https://github.com/eldarion/eldarion-ajax-demo/ which is also online at http://uk013.gondor.co/

Installation

jQuery is required for this library so make sure it is included somewhere on the page prior to the inclusion of eldarion-ajax.min.js.

Copy js/atb-ajax.min.js to where you keep your web sites static media and the include them in your HTML:

<script src="/js/atb-ajax.js"></script>

Actions

There are currently three actions supported:

1. a.click
2. form.submit
3. a.cancel

a.click

Binding to the a tag's click event where the tag has the class ajax:

<a href="/tasks/12342/done/" class="btn ajax">
    <i class="icon icon-check"></i>
    Done
</a>

In addition to the href attribute, you can add data-method="post" to change the default action from an HTTP GET to an HTTP POST.

form.submit

Convert any form to an AJAX form submission quite easily by adding ajax to the form's class attribute:

<form class="form ajax" action="/tasks/create/" method="post">...</form>

When submitting this form the data in the form is serialized and sent to the server at the url defined in action using the method that was declared in the form tag.

a.cancel

Any a tag that has a data-cancel-closest attribute defined will trigger the cancel event handler. This simply removes from the DOM any elements found using the selector defined in the data-cancel-closest attribute:

<a href="#" data-cancel-closest=".edit-form" class="btn">
    Cancel
</a>

Events

There are three custom events that get triggered allowing you to customize the behavior of eldarion-ajax.

1. eldarion-ajax:begin
2. eldarion-ajax:success
3. eldarion-ajax:error
4. eldarion-ajax:complete
5. eldarion-ajax:modify-data

All events are triggered on the element that is declared to be ajax. For example, if you had a <a href="/tasks/2323/delete/" class="ajax" data-method="post"> link, the trigger would be fired on the <a> element. This, of course, bubbles up, but allows you to easily listen only for events on particular tags.

Every event also sends as its first parameter, the element itself, in case you were listening at a higher level in the chain, you still would have easy access to the relevant node.

eldarion-ajax:begin

This is the first event that fires and does so before any ajax activity starts. This allows you to setup a spinner, disable form buttons, etc. before the requests starts.

A single argument is sent with this event and is the jQuery object for the node:

$(document).on("eldarion-ajax:begin", function(evt, $el) {
    $el.html("Processing...");
});

eldarion-ajax:success

This event is triggered if the request succeeds. Four arguments are passed with this event: the jQuery object; the data returned from the server; a string describing the status; and the jqXHR object:

$(document).on("eldarion-ajax:success", "[data-prepend-inner]", function(evt, $el, data, textStatus, jqXHR) {
    var $node = $($el.data("prepend-inner"));
    $node.data(data.html + $node.html());
});

eldarion-ajax:error

This event is triggered if the request fails. Four arguments are also passed with this event: the jQuery object, the jqXHR object; a string describing the type of error that occurred; and an optional exception object. Possible values for the third argument (besides null) are "timeout", "error", "abort", and "parsererror". When an HTTP error occurs, the fourth argument receives the textual portion of the HTTP status, such as "Not Found" or "Internal Server Error."

eldarion-ajax:complete

This event is triggered when the request finishes (after the above success and error events are completed). This is triggered from the document rather than the element in context as the handlers processing success messages could replace the DOM element and therefore would prevent the event from reaching your listener. The element is always passed as the first argument with this event (even if it no longer exists in the DOM). In response to a successful request, the arguments passed with this event are the same as those of the success event: the element, data, textStatus, and the jqXHR object. For failed requests the arguments are the same as those of the error event: the element, the jqXHR object, textStatus, and errorThrown.

eldarion-ajax:modify-data

This is triggered with jQuery's triggerHandler so it functions more like a callback. If you listen for it, you have to listen on the same element that you have wired up to send AJAX data on as the event doesn't bubble up. Also, it will send the original data that it serialized as a parameter and if you want to change the data at all, you must return new data from the function handling the event. Otherwise, the original data will be used.

Handlers: A Framework

The events provided above allow you to roll your own handlers in such a way to really customize how you want your application to respond to server responses. A lot have been provided (see the section below), but here is a quick primer on writing your own.

$(function ($) {
    CustomHandlers = {};
    
    CustomHandlers.prototype.replaceFadeIn = function (e, $el, data) {
        $($el.data("replace-fade-in")).replaceWith(data.html).hide().fadeIn();
    };
    
    $(function() {
        $(document).on("eldarion-ajax:success", "[data-replace-fade-in]", CustomHandlers.prototype.replaceFadeIn);
    });
}(window.jQuery));

This gives you a lot of flexibility. For example, if you don't like how the batteries included approach treats server response data, you can drop the inclusion of eldarion-ajax-handlers.js and roll your own.

Handlers: Batteries Included

There are three data attributes looked for in the response JSON data:

1. location
2. html
3. fragments

If location is found in the response JSON payload, it is expected to be a URL and the browser will be immediately redirected to that location. If, on the other hand it is not present, then the processing rules below will be processed based on what attributes are defined.

If you have a fragments hash defined, it should contain a list of key/value pairs where the keys are the selectors to content that will be replaced, and the values are the server-side rendered HTML content that will replace the elements that match the selection.

You can define both html to be processed by the declaritive rules defined below and the fragements at the same time. This gives you the ability to for example replace the form you submited with html content while at the same time updating multiple bits of content on the page without having to refresh them.

There are five different ways that you can declare an html response without a location directive be processed:

1. Append
2. Refresh
3. Refresh Closest
4. Replace
5. Replace Closest

Here is where it can get fun as all of the values for these processing directives are just CSS selectors. In addition they can be multiplexed. You can declare all of them at the same time if you so desire. A CSS selector can easily be written to address multiple different blocks on the page at the same time.

Best to just see some examples.

Append

Using data-append allows you to specify that the data.html returned in the server response's JSON be appended to the elements found in the specified CSS selector:

<a href="/tasks/12342/done/" class="btn ajax" data-method="post"
                                              data-append=".done-list">
    <i class="icon icon-check"></i>
    Done
</a>

Refresh

Using the data-refresh attribute lets you define what elements, if selected by the CSS selector specified for its value, get refreshed. Elements that are selected will get refreshed with the contents of the url defined in their data-refresh-url attribute:

<div class="done-score" data-refresh-url="/users/paltman/done-score/">...</div>

<div class="done-list">...</div>

<a href="/tasks/12342/done/" class="btn ajax" data-method="post"
                                              data-append=".done-list"
                                              data-refresh=".done-score">
    <i class="icon icon-check"></i>
    Done
</a>

In this example, the .done-list will be appended to with the data.html returns from the AJAX post made as a result of clicking the button and simultaneously, the .done-score will refresh itself by fetching (GET) JSON from the url defined in data-refresh-url and replacing itself with the contents of data.html that is returned.

Refresh Closest

This works very much in the same way as data-refresh however, the uses jQuery's closest method to interpret the selector.

Replace

Sometimes you want to neither refresh nor append to existing elements but you want to just replace the content with whatever it is that is returned from the server. This is what data-replace is for.

Replace Closest

This works very much in the same way as data-replace however, the uses jQuery's closest method to interpret the selector.

<div class="done-score" data-refresh-url="/users/paltman/done-score/">...</div>

<div class="done-list">...</div>

<div class="results"></div>

<a href="/tasks/12342/done/" class="btn ajax" data-method="post"
                                              data-append=".done-list"
                                              data-refresh=".done-score"
                                              data-replace=".results">
    <i class="icon icon-check"></i>
    Done
</a>

It is rare that you'll add/use all of these processing methods combined like this. Usually it will just be one or the other, however, I add them all here to illustrate the point that they are independently interpreted and executed.

Commercial Support

This project, and others like it, have been built in support of many of Eldarion's own sites, and sites of our clients. We would love to help you on your next project so get in touch by dropping us a note at info@eldarion.com.