getTargetFilePath(fileName,noPrompt) {
        var self = this;
        return new Promise((resolve, reject) => {
            var file = new File(new Array(),fileName);
            browser.downloads.download({
                url: URL.createObjectURL(file),
                conflictAction: "uniquify",
                filename: fileName,
                saveAs: !noPrompt,
            })
            .then((downloadId)=>{
                var listenerInstalled = false;
                var resolved = false;

                function RemoveListener() {
                    if(listenerInstalled) {
                        browser.downloads.onChanged.removeListener(Listener);
                        listenerInstalled = false;
                    }
                }

                function Resolve(filePath) {
                    if(!resolved) {
                        resolved = true;
                        if(filePath)
                            self.hit.targetDirectory =
                                /^(.*?)[^\\\/]*$/.exec(filePath)[1];
                        resolve(filePath);
                    }
                }

                function Listener(details) {
                    if(details.id==downloadId) {
                        if(details.error) {
                            // Chrome specifies error on user cancel
                            RemoveListener();
                            Resolve(null);
                        } else if(details.filename && details.filename.current) {
                            RemoveListener();
                            Resolve(details.filename.current);
                        }
                    }
                }

                browser.downloads.search({
                    id: downloadId
                })
                .then((downloadItems)=>{
                    // Firefox resolves the search once use chose file
                    var downloadItem = downloadItems[0];
                    if(downloadItem && downloadItem.filename) {
                        RemoveListener();
                        Resolve(downloadItem.filename);
                    }
                });

                browser.downloads.onChanged.addListener(Listener);
                listenerInstalled = true;
            })
            .catch((err)=>{
                // Firefox generates exception on user cancel
                resolve(null);
            });
        });
    }