plugins.md

How to create a plugin

That's actually how Ajax plugin is implemented. It's quite simple and you can learn everything you need to know about plugins from its implementation.

(function () {
    // Adding information about ourselvels to plugin list.
    // Instead of true we could supply plugin version here
    atom.plugins['ajax'] = true;

    // this will be atom.ajax(config)
    var ajax = function (userConfig) {
        // default options
        var config = atom.extend({
            interval : 0,
            type     : 'plain',
            method   : 'post',
            url      : location.href,
            onLoad   : function(){},
            onError  : function(){}
        }, userConfig);

        // no support for old browsers ;-)
        var req = new XMLHttpRequest();
        req.onreadystatechange = ajax.onready;
        req.open(config.method.toUpperCase(), config.url, true);
        req.send(null);
    };

    // use small methods to allow easy customization of behavior
    ajax.onready = function (e) {
        if (req.readyState == 4) {
            if (req.status != 200) return config.onError(e);

            var result = req.responseText;
            if (config.type.toLowerCase() == 'json') {
                result = JSON.parse(result);
            }
            if (config.interval > 0) setTimeout(function () {
                atom.ajax(config);
            }, config.interval * 1000);
            config.onLoad(result);
        };
    };

    // adding method to Atom
    atom.extend({ ajax : ajax });
})();

Now we want to have a support for using Ajax with DOM plugin:

// that's from previous piece of code, so you can understand where we're
// adding that stuff :)
atom.extend({ ajax : ajax });

// only if plugin 'dom' is present
if (atom.plugins['dom']) {
    // extending prototype this time
    atom.implement({
        ajax : function (config) {
            config = extend({}, config);

            // please note that callback, passed by user, will be called
            // in atom() element context
            atom.ajax(extend(config, {
                // use user supplied callback or just update element contents
                onLoad  : (config.onLoad || function (res) {
                    this.get().innerHTML = res;
                }).bind(this),
                onError : (config.onError || function(){}).bind(this)
            }));
            return this;
        }
    });
}