I have been trying to create a custom textfield in tapestry which will render some javascript when it gains focus. But I have been having trouble trying to find an example of this.

Here is some of the code i have started off with:

package asc.components;

import org.apache.tapestry5.ComponentResources;
import org.apache.tapestry5.Field;
import org.apache.tapestry5.annotations.Parameter;
import org.apache.tapestry5.ioc.annotations.Inject;
import org.apache.tapestry5.services.ComponentDefaultProvider;


public class DahserTextField implements Field {

@Parameter (defaultPrefix = "literal")
private String label;
@Inject
private ComponentResources resources;
@Inject
private ComponentDefaultProvider defaultProvider;
@Parameter
private boolean disabled;
@Parameter
private boolean required;

String defaultLabel(){
    return defaultProvider.defaultLabel(resources);
}

public String getControlName() {
    return null;
}

public String getLabel() {
    return label;
}

public boolean isDisabled() {
    return disabled;
}

public boolean isRequired() {
    return required;
}

public String getClientId() {
    return resources.getId();
}


}

I have been unsure on what to do next. I do not know what to put into the .tml file. I would be grateful if anyone could help or point me in the right direction.