How to Keep Tabs on a Particular Tab? - firefox-addon-sdk

Question

In my firefox sdk addon, I want to use a custom webpage from my data directory as my settings/about page.
But I am having trouble keeping tabs on the tab!
So I have a button that calls the OptionsPanel() function to open my webpage in a new tab. Now, I want to make it so if the user forgets that tab is open and pushes the button again, that it activates the already-open settings tab. That means I need to know that the tab is open and I need to be able to switch to it if it is OR open it if it is not already open.
Here is what I've come up with so far, but it doesn't work; it just always opens a new tab. I don't even know if I'm barking up the right tree.
const tabs = require("sdk/tabs");
var optionsTab;
function OptionsPanel(){
var opsTab = GetTabByID(optionsTab.id);
if(opsTab == null){
tabs.open( data.url("OptionsPanel.html") );
optionsTab.id = tabs.tab.id; <======errors out as undefined
}else{
opsTab.activate();
}
}
//return a handle to the tab that matches specified tab id
function GetTabByID(whatid){
for(let thistab of tabs){
if(thistab.id = whatid){
return thistab;
}
}
return null;
}
So, here are my goals:
Open my page in a new tab if it isn't already open.
If the tab is already open, then switch to that tab.
If the page is open when the browser loads, then be ready to switch to that tab if the user pushes the options button.

Answer 1

Why would you think tabs module has a tab property?
Normally you would use the activeTab property instead. However it does not get updated immediately after tabs.open is called. One has to use tabs[tabs.length - 1] instead.
const tabs = require("sdk/tabs");
var optionsTabId;
function OptionsPanel(){
var opsTab = GetTabByID(optionsTabId);
if (opsTab == null) {
tabs.open( data.url("OptionsPanel.html") );
optionsTabId = tabs[tabs.length - 1].id;
} else {
opsTab.activate();
}
}
Additionally, you made a mistake in GetTabByID.
//return a handle to the tab that matches specified tab id
function GetTabByID(whatid){
for(let thistab of tabs){
if(thistab.id == whatid){ // use == to compare
return thistab;
}
}
return null;
}
Keep in mind this assumes that it is not possible to navigate away from your options tab. I would check optsTab.url just in case.
Alternatively you could make use of the tab event interface
const tabs = require("sdk/tabs");
const OPTIONS_URL = data.url("OptionsPanel.html");
var optionsTab = null;
function OptionsPanel(){
if (optionsTab == null) {
tabs.open(OPTIONS_URL);
tabs.once('ready', function(tab) {
optionsTab = tab;
optionsTab.on('ready', function readyListener(tab) {
if (tab.url !== OPTIONS_URL) {
optionsTab.off('ready', readyListener);
optionsTab = null;
}
})
optionsTab.once('close', function(tab) {
optionsTab = null;
})
});
} else {
optionsTab.activate();
}
}