Run Ajax without jQuery

Use this when you want your pages to stop downloading jQuery: to send less JavaScript, or to drop a third-party library you do not use yourself. Wicket 11 ships two implementations of its client-side Ajax library with the same JavaScript API (Wicket.Ajax, Wicket.Event, Wicket.DOM, Wicket.Form, Wicket.Head, Wicket.Focus and the rest). The default, wicket-ajax-jquery.js, is built on jQuery. wicket-ajax.js uses only browser APIs. Java code does not notice the difference.

Switch the application to the plain JavaScript implementation

Set the Ajax reference in your application’s init():

WicketApplication.java

@Override
protected void init() {
    super.init();
    getJavaScriptLibrarySettings()
        .setWicketAjaxReference(WicketAjaxResourceReference.get());
}

Pages now contribute wicket-ajax.js instead of jQuery and wicket-ajax-jquery.js. Check it in the browser’s network panel: no jquery file is loaded unless something else asks for it. To switch back, remove the line or set WicketAjaxJQueryResourceReference.get(), which is the default.

What keeps working

Every component and behavior that talks to the browser through the Wicket.* API depends on the configured reference, not on jQuery, and needs no further change. This covers all Ajax components and behaviors in wicket-core, and in wicket-extensions among others AutoCompleteTextField, Palette, UploadProgressBar, AjaxDownloadBehavior, ModalDialog with its TrapFocusBehavior, and the veil behaviors. The DebugBar of wicket-devutils works with both.

Pages with a WebSocketBehavior still need jQuery: the setup script that wicket-native-websocket renders calls jQuery.extend. Render the jQuery reference from those pages as shown below.

Keep jQuery for your own scripts

The switch only removes Wicket’s own use of jQuery. JavaScript of your own, or of a library, that calls $(...) or jQuery(...) still needs it. Render the jQuery reference from the component that needs it, as for any other library:

@Override
public void renderHead(IHeaderResponse response) {
    super.renderHead(response);
    response.render(JavaScriptHeaderItem.forReference(
        getApplication().getJavaScriptLibrarySettings().getJQueryReference()));
    response.render(JavaScriptHeaderItem.forReference(MY_WIDGET_JS));
}

In Wicket 11 that reference is jQuery 4.0. A script that still needs jQuery 3 can have it application-wide with getJavaScriptLibrarySettings().setJQueryReference(JQueryResourceReference.getV3()).

Better still, declare jQuery as a dependency of your script’s resource reference, so every page that uses the script loads jQuery first; see Declare dependencies between resources.

Check your JavaScript callbacks

Code that only uses the documented Wicket.* functions runs unchanged. Look at code that uses what the jQuery implementation hands to callbacks:

• In call listener handlers, jqXHR is a plain XMLHttpRequest and settings a plain object. jQuery methods on them, such as jqXHR.done(), are not there.
• Subscribers registered with Wicket.Event.subscribe get a small plain event object as their first argument instead of a jQuery event. The other arguments are the same.
• Elements passed to /dom/node/added and /dom/node/removing subscribers are DOM elements in both implementations.

See React to Ajax requests in JavaScript for the handlers and events. How Wicket Ajax works explains what the library does during a request.