How to remove an event listener? - firefox

Question

I use the Mozilla's Add-on Builder. I am looking for a way to remove an event listener in a contentScript. I use the port way to communicate between add-on script code and the content script code.
The problem is the callback on event "response" is called more than once. I want it to be called once and declared in the callback of the event show.
Can someone help me with that?
main.js code:
var Panel = require("panel").Panel;
var popup_panel = Panel({
width: 286,
height: 340,
contentURL: require("self").data.url("popup.html"),
allow: { script: true },
contentScriptWhen: "end",
contentScriptFile : [
require("self").data.url("test.js")
],
onShow: function(){
this.port.emit("show");
var pan = this;
this.port.on("hide", function(){pan.hide();});
}
});
var Widget = require("widget").Widget;
var widget = Widget({
id: "mozilla-icon",
label: "My Mozilla Widget",
contentURL: "http://www.mozilla.org/favicon.ico",
panel: popup_panel
});
popup_panel.port.on("get", function(){
popup_panel.port.emit("response");
});
Content script (test.js):
self.port.on("show", function(){
console.log("show");
function response(){
console.log("reponse called");
}
self.port.emit("get");
self.port.once("response", response);
self.port.removeListener("response", response);
});
full source code

Answer 1

Finally I found the problem. It is a bug in the add-on kit. In the file api-utils/lib/content/content-worker.js in the function removeListener the index is always -1.
The parameter given in the indexOf is the name of the event and it search a function. It is incorrect.
So to solve the problem I replace the line let index = listeners[name].indexOf(name); by let index = listeners[name].indexOf(callback);.
EDIT
The bug has been fixed. It will publish in the version 1.10 see here