XPages: An optimized JavaScript Resource Renderer

Ferry Kranenburg created a nice hack to solve the AMD loader problem with XPages and Dojo, and because of the missing ability to add a resource to the bottom of an XPage by a property, I have created a new JavaScriptRenderer which allows to control where a CSJS script will be rendered.

The renderer has multiple options:

  • NORMAL – handles the CSJS resource as always
  • ASYNC – loads the script in an asynchronous way (with an own script tag)
  • NOAMD – adds the no amd scripts around the resource
  • NORMAL_BOTTOM – adds the script at the bottom of the <body> tag
  • ASYNC_BOTTOM – async, but at the end of the generated HTML page
  • NOAMD_BOTTOM – at the end, with the surrounding no amd scripts

To use the normal mode, you don’t have to change you resource definition. If you want to use the other modes, you have to change the content type of the resource with one of the entries in the list above. This for example would add a script block to the end of the page, including the non amd script blocks around it:

<?xml version="1.0" encoding="UTF-8"?>
<xp:view xmlns:xp="http://www.ibm.com/xsp/core">
    <xp:this.resources>
        <xp:script clientSide="true" type="NOAMD_BOTTOM">
            <xp:this.contents><![CDATA[alert("Hello World!");]]></xp:this.contents>
        </xp:script>
    </xp:this.resources>
</xp:view>

2015-06-21 11_04_09

Here is the code for the resource renderer:

package ch.hasselba.xpages;

import java.io.IOException;
import java.util.Iterator;
import java.util.Map;

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;

import com.ibm.xsp.component.UIViewRootEx;
import com.ibm.xsp.renderkit.html_basic.ScriptResourceRenderer;
import com.ibm.xsp.resource.Resource;
import com.ibm.xsp.resource.ScriptResource;
import com.ibm.xsp.util.JSUtil;

public class OptimizedScriptResourceRenderer extends ScriptResourceRenderer {
    private static final String TYPE = "type";
    private static final String SCRIPT = "script";
    private static final String CSJSTYPE = "text/javascript";
    private boolean isBottom = false;
    
    private static enum Mode {
        NORMAL, ASYNC, NOAMD, ASYNC_BOTTOM, NOAMD_BOTTOM, NORMAL_BOTTOM
    }

    public void encodeResourceAtBottom(FacesContext fc,
            UIComponent uiComponent, Resource resource) throws IOException {
        isBottom = true;
        encodeResource(fc, uiComponent, resource);
        isBottom = false;
    }

    @Override
    public void encodeResource(FacesContext fc, UIComponent uiComponent,
            Resource resource) throws IOException {

        ScriptResource scriptResource = (ScriptResource) resource;
        ResponseWriter rw = fc.getResponseWriter();
        String type = scriptResource.getType();
        String charset = scriptResource.getCharset();
        String src = scriptResource.getSrc();

        Mode mode = Mode.NORMAL;
        try{
            mode = Mode.valueOf( type );
        }catch(Exception e){};

        if (mode == Mode.NORMAL || mode == Mode.NORMAL_BOTTOM ) {
            normalBottomJSRenderer( fc, uiComponent, scriptResource, (mode == Mode.NORMAL_BOTTOM), type );
        } else {
            if (mode == Mode.ASYNC || mode == Mode.ASYNC_BOTTOM) {
                asyncJSRenderer(fc, uiComponent, scriptResource, (mode == Mode.ASYNC_BOTTOM), rw, type,
                        charset, src );
            }else if (mode == Mode.NOAMD || mode == Mode.NOAMD_BOTTOM ) {
                noAMDJSRenderer(fc, uiComponent, scriptResource, (mode == Mode.NOAMD_BOTTOM) , rw, 
                        type, charset, src);
            }

        }

    }

    private void normalBottomJSRenderer(FacesContext fc,UIComponent uiComponent,
            ScriptResource scriptResource, final boolean addToBottom, final String type ) throws IOException {
        
        if( addToBottom && !isBottom )
            return;
        scriptResource.setType(null);
        super.encodeResource(fc, uiComponent, scriptResource);
        scriptResource.setType(type);
        
    }
    private void asyncJSRenderer(FacesContext fc,
            UIComponent uiComponent, ScriptResource scriptResource, 
             final boolean addToBottom, ResponseWriter rw, final String type, final String charset,
            final String src) throws IOException {
        
        if( addToBottom && !isBottom )
            return;
        
        Map<String, String> attrs = null;
        String key = null;
        String value = null;
        String id = "";

        if (scriptResource.getContents() == null) {
            attrs = scriptResource.getAttributes();
            if (!attrs.isEmpty()) {
                StringBuilder strBuilder = new StringBuilder(124);
                for (Iterator<String> it = attrs.keySet().iterator(); it
                        .hasNext();) {
                    key = it.next();
                    value = attrs.get(key);
                    strBuilder.append(key).append('(').append(value)
                            .append(')');
                }
                id = strBuilder.toString();
            }

            // check if already added
            UIViewRootEx view = (UIViewRootEx) fc.getViewRoot();

            String resId = "resource_" + ScriptResource.class.getName() + src
                    + '|' + type + '|' + charset + id;
            if (view.hasEncodeProperty(resId)) {
                return;
            }
            view.putEncodeProperty(resId, Boolean.TRUE);

        }
        if (!scriptResource.isClientSide()) {
            return;
        }

        rw.startElement(SCRIPT, uiComponent);
        JSUtil.writeln(rw);
        rw.write("var s = document.createElement('" + SCRIPT + "');");
        JSUtil.writeln(rw);
        rw.write("s.src = '" + src + "';");
        JSUtil.writeln(rw);
        rw.write("s.async = true;");
        JSUtil.writeln(rw);
        rw.write("document.getElementsByTagName('head')[0].appendChild(s);");
        JSUtil.writeln(rw);
        rw.endElement(SCRIPT);
        JSUtil.writeln(rw);
    }

    
    private void noAMDJSRenderer(FacesContext fc,
             UIComponent uiComponent,ScriptResource scriptResource,
            final boolean addToBottom, ResponseWriter rw, final String type, final String charset,
            final String src ) throws IOException {
        
        if( addToBottom && !isBottom )
            return;

        // write the "disable AMD" script
        rw.startElement(SCRIPT, uiComponent);
        rw.writeAttribute(TYPE, CSJSTYPE, TYPE);
        rw.writeText(
                        "'function'==typeof define&&define.amd&&'dojotoolkit.org'==define.amd.vendor&&(define._amd=define.amd,delete define.amd);",
                        null);
        rw.endElement(SCRIPT);
        JSUtil.writeln(rw);

        // write the normal CSJS
        scriptResource.setType(null);
        super.encodeResource(fc, uiComponent, scriptResource);
        scriptResource.setType(type);
        // write the "reenable AMD" script
        rw.startElement(SCRIPT, uiComponent);
        rw.writeAttribute(TYPE, CSJSTYPE, TYPE);
        rw
                .writeText(
                        "'function'==typeof define&&define._amd&&(define.amd=define._amd,delete define._amd);",
                        null);
        rw.endElement(SCRIPT);
        JSUtil.writeln(rw);

    }
}

The ViewRenderer must also be modified, otherwise it is not possible to add the resources at the bottom of the <body> tag:

package ch.hasselba.xpages;

import java.io.IOException;
import java.util.List;

import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;
import javax.faces.render.Renderer;

import com.ibm.xsp.component.UIViewRootEx;
import com.ibm.xsp.render.ResourceRenderer;
import com.ibm.xsp.renderkit.html_basic.ViewRootRendererEx2;
import com.ibm.xsp.resource.Resource;
import com.ibm.xsp.resource.ScriptResource;
import com.ibm.xsp.util.FacesUtil;

public class ViewRootRendererEx3 extends ViewRootRendererEx2 {

    protected void encodeHtmlEnd(UIViewRootEx uiRoot, ResponseWriter rw)
            throws IOException {
        FacesContext fc = FacesContext.getCurrentInstance();

        List<Resource> resources = uiRoot.getResources();
        for (Resource r : resources) {
            if (r instanceof ScriptResource) {
                ScriptResource scriptRes = (ScriptResource) r;
                if (scriptRes.isRendered()) {
                    Renderer renderer = FacesUtil.getRenderer(fc, scriptRes.getFamily(), scriptRes.getRendererType());
                    ResourceRenderer resRenderer = (ResourceRenderer) FacesUtil.getRendererAs(renderer, ResourceRenderer.class);
                    if( resRenderer instanceof OptimizedScriptResourceRenderer ){
                        ((OptimizedScriptResourceRenderer) resRenderer).encodeResourceAtBottom(fc, uiRoot, r);
                    }
                }
            }
        }

        rw.endElement("body");
        writeln(rw);
        rw.endElement("html");
    }

}

To activate the new renderes, you have to add them to the faces-config.xml:

<?xml version="1.0" encoding="UTF-8"?>
<faces-config>
  <render-kit>
    <renderer>
      <component-family>com.ibm.xsp.resource.Resource</component-family>
      <renderer-type>com.ibm.xsp.resource.Script</renderer-type>
      <renderer-class>ch.hasselba.xpages.OptimizedScriptResourceRenderer</renderer-class>
    </renderer>
    <renderer>
      <component-family>javax.faces.ViewRoot</component-family>
      <renderer-type>com.ibm.xsp.ViewRootEx</renderer-type>
      <renderer-class>ch.hasselba.xpages.ViewRootRendererEx3</renderer-class>
    </renderer>
  </render-kit>
</faces-config>

Needless to say that this works in Themes too.

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8 Kommentare zu XPages: An optimized JavaScript Resource Renderer

  1. Michael Bourak sagt:

    Nice and useful !

  2. Perhaps push this as an enhancement request to the extension library 😉
    This would be a really good addition

  3. Fredrik Stöckel sagt:

    Very nice and useful – nice work!

    btw, while on the subject, do you know if there a way to control how all the inline (redundant) js event code gets rendered?

    • Which code do you mean? The CSJS code generated for the XspEventHandlers?

      • Fredrik Stöckel sagt:

        Yes, exactly – the CSJS code that gets generated when assigning events to buttons et al. It’s often a repeat of the „same“ logic and the source ends up looking way messy (imho), with probably more „dead code“ than necessary.

        I haven’t given this any further thoughts – it was an idea I got when I saw your awesome resource renderer 🙂 but it would be more optimal if al such code was moved to a separate js resource file that is automatically generated and included when the page is complied. This would reduce the amount of „dead-code“ on the page and also make it available for caching and so on…

        I guess it would be challenging to control and move csjs code that’s included „on the fly“ from a partial update or similar – unless one can use some „live“ event assignments and apply listeners dynamically depending on whats displayed on the page. That would probably require a complete rewrite of the event logic..

  4. Great work, thank you for sharing!!

    My first findings after some testing is, that when I add a resource – even without a type tag – it gets always added to the body’s bottom. This means, output scripts of the xpages are executed first in any case. Should it be like that?

    • Thanks for your feedback. I have to check this issue.

      • Ok, after some hard thinking, I’ve found out, that the encodeResourceAtBottom method of the OptimizedScriptResourceRenderer should be used for bottom scripts only 😀
        I changed

        if( resRenderer instanceof OptimizedScriptResourceRenderer ){
        ((OptimizedScriptResourceRenderer) resRenderer).encodeResourceAtBottom(fc, uiRoot, r);
        }

        to

        if( resRenderer instanceof OptimizedScriptResourceRenderer ){

        String type = ((ScriptResource) r).getType();
        Mode mode = Mode.NORMAL;
        try{
        mode = Mode.valueOf( type );
        }catch(Exception e){};

        if (mode == Mode.NORMAL_BOTTOM || mode == Mode.ASYNC_BOTTOM || mode == Mode.NOAMD_BOTTOM ) {
        ((OptimizedScriptResourceRenderer) resRenderer).encodeResourceAtBottom(fc, uiRoot, r);
        }
        }

        and it works for me. Only the *_BOTTOM type scripts appear at the end of the body. All others, including noamd and async are within the head.

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