`gs.content.js.loader` API¶

In GroupServer a page may be made up of multiple components that are quite separate from each other. A common pattern is for some a component to add some HTML to the page, and then to inject some JavaScript code into the bottom of the page. Each component is usually unaware of what modules have been loaded by the other components. To get around this global tracking of loaded modules prevents modules from being loaded and parsed unnecessarily. While originally written for GroupServer, there is nothing specific to GroupServer in this product.

gsJsLoader¶: The global object (singleton) that keeps track of what is loaded.

The gsJsLoader.with_module() method of the gsJsLoader object loads one or more resources and runs a function afterwards. Introspection is provided by the gsJsLoader.loaded(), gsJsLoader.loading() and gsJsLoader.exists() methods.

gsJsLoader.with_module(url | [url1, url2… urlN], fn)¶

Arguments:	url (string) – The URL of the module you wish to load. If a list of URLs is supplied each module is loaded in sequence. fn (function) – The function to execute after the module has loaded. (Usually this is the code that depends on the module.) If a list of URLs is supplied as the first argument then the function is executed after all the modules have been loaded.
Returns:	Nothing.

With some modules run a function.

If the module has not been loaded and not been requested:

Inserts <script> elements into the <head> of the document, to cause the module or modules specified in url to load.

Connects the function to the load (or onload for older versions of Internet Explorer) callback of the <script>.

If the module has been requested, but has not been loaded:

Connects the function to the load callback of the <script>.

If the module has been loaded:

Calls the function.

gsJsLoader.loaded(url)¶

Arguments:	url (string) – The URL of the module to test.
Returns:	`true` if the module has been loaded; `false` if the module is being loaded or has yet to be requested.
Return type:	boolean

This function tests if a module has been loaded (past-tense).

gsJsLoader.loading(url)¶

Arguments:	url (string) – The URL of the module to test.
Returns:	`true` if the module is being loaded; `false` if the module has been loaded or has not been requested.
Return type:	boolean

Test if a module is being loaded (present continuous tense).

gsJsLoader.exists(url)¶

Arguments:	url (string) – The URL of the module to test.
Returns:	`true` if the module has being loaded or has been requested; `false` otherwise.
Return type:	boolean

Test if a module is known (it has either been loaded, or is being loaded).

Examples¶

Run the function init_topic_search with the base search code:

gsJsLoader.with_module('/++resource++gs-search-base-js-20121217.js',
                       init_topic_search);

Load two modules, jQuery and then Twitter Bootstrap. Execute the function my_code after both modules have been loaded.

gsJsLoader.with_module(['/++resource++jquery-1.8.3.js',
                        '/++resource++bootstrap-2.2.2/js/bootstrap.js'],
                       my_code);

Wait for the window to load, then initialise the post searching code. Detect and support loading if we are using a version of Microsoft Internet Explorer that does not support the standard addEventListener method:

if (window.addEventListener) {
    window.addEventListener('load', function () {
        gsJsLoader.with_module(
            '/++resource++gs-search-base-js-20121217.js',
            init_post_search);
    }, false);

} else {
    window.attachEvent('onload', function () {
        gsJsLoader.with_module(
            '/++resource++gs-search-base-js-20121217.js',
            init_post_search);
    });
}

The same call as above, but using jQuery to attach to the load event:

jQuery(window).load(function () {
          gsJsLoader.with_module(
              '/++resource++gs-search-base-js-20121217.js',
              init_post_search);
 });

(This module is devoid of jQuery code, so it can be used to load jQuery.)

gs.content.js.loader API¶

Examples¶

`gs.content.js.loader` API¶