Can you load the PopupAppender on demand? - log4javascript

Question

I am trying to use log4javascript and was wondering if there is any way to load the PopupAppender on demand.
I am seeking functionality much like the in-browser tools, where there would be an icon in my application that indicates that something has been logged and when I click it, the PopupAppender opens and allows me to view the logs.
I'm thinking I could write my own very simple appender to show the icon if there are errors, but i'm not sure how I could load up the PopupAppender and show historic messages?

Answer 1

You'd have to have some kind of proxy appender, as you suggest, which stores logging messages and creates a PopUpAppender on demand. Something like this:
Demo: http://jsfiddle.net/hDRpT/
Code:
function OnDemandPopUpAppender() {
this.popUpAppender = new log4javascript.PopUpAppender();
this.poppedUp = false;
this.popperUpperDisplayed = false;
this.queuedLoggingEvents = [];
}
var proto = new log4javascript.Appender();
OnDemandPopUpAppender.prototype = proto;
proto.appendQueued = function() {
for (var i = 0, loggingEvent; loggingEvent = this.queuedLoggingEvents[i++]; ) {
this.popUpAppender.append(loggingEvent);
}
this.queuedLoggingEvents.length = 0;
};
proto.popUp = function() {
this.poppedUp = true;
this.appendQueued();
};
proto.append = function(loggingEvent) {
var appender = this;
this.queuedLoggingEvents.push(loggingEvent);
if (this.poppedUp) {
this.appendQueued();
} else if (!this.popperUpperDisplayed &&
loggingEvent.level.isGreaterOrEqual(log4javascript.Level.ERROR)) {
var popperUpper = document.createElement("div");
popperUpper.style.border = "solid red 2px";
popperUpper.innerHTML = "There are error messages in the log. Click to open.";
popperUpper.onclick = function() {
appender.popUp();
}
document.body.appendChild(popperUpper);
this.popperUpperDisplayed = true;
}
};
var log = log4javascript.getLogger("main");
log.addAppender(new OnDemandPopUpAppender());
log.debug("A debug message");
log.error("A horrible error!");