f:ajax - add onprogress attribute to let the dev pass a js callback

[pizzi80]

This is a missing part of the javascript ajax engine of Faces

to be on par with the standard XMLHttpRequest

https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequestEventTarget/progress_event

<f:ajax onprogress="console.log(data.percentage)" />

public class AjaxBehavior extends ClientBehaviorBase {

    enum PropertyKeys {
        // ... 
        onprogress
    }

    public String getOnprogress() {
        return (String) getStateHelper().eval(PropertyKeys.onprogress);
    }

    public void setOnprogress(String onprogress) {
        getStateHelper().put(PropertyKeys.onprogress, onprogress);
    }
}

[pizzi80]

bonus for file upload

expose the XMLHttpRequestUpload object to the Faces "data" js object

The XMLHttpRequest upload property returns an XMLHttpRequestUpload object that can be observed to monitor an upload's progress.