How to load a JavaScript file on all pages programmatically

Question

I have a jsf jar library, and I want to load a specific JavaScript file (exist in the jar) in all pages of the JSF 2.2 project that use it, and without any additional configuration.

I want to load a specific JavaScript file exist in my library without use of h:outputScript tag in the page( Neither the template nor the page )

Is this possible in jsf web application?

Answer 1

You can use UIViewRoot#addComponentResource() to programmatically add JSF resources. You can use a SystemEventListener on PostAddToViewEvent of <h:head> for this.

public class DynamicHeadResourceListener implements SystemEventListener {

    @Override
    public boolean isListenerForSource(Object source) {
        return "javax.faces.Head".equals(((UIComponent) source).getRendererType());
    }

    @Override
    public void processEvent(SystemEvent event) {
        String library = "yourLibraryName";
        String name = "yourScript.js"; // Can be dynamic here.
        addHeadResource(FacesContext.getCurrentInstance(), library, name);
    }

    private void addHeadResource(FacesContext context, String library, String name) {
        UIComponent resource = new UIOutput();
        resource.getAttributes().put("library", library);
        resource.getAttributes().put("name", name);
        resource.setRendererType(context.getApplication().getResourceHandler().getRendererTypeForResourceName(name));
        context.getViewRoot().addComponentResource(context, resource, "head");
    }
}

In order to get it to run, register it in faces-config.xml of your module project as below:

<system-event-listener>
    <system-event-listener-class>com.example.DynamicHeadResourceListener</system-event-listener-class>
    <system-event-class>javax.faces.event.PostAddToViewEvent</system-event-class>
    <source-class>javax.faces.component.UIOutput</source-class>
</system-event-listener>