I want to save user settings for my firefox add-on in a variable which can be accessible any time I want. It should not get vanished on browser clos. Now how can I do it?

I have tried "simple-storage" module of firefox, it works fine until I quit my browser. When I quit my browser, "simple-storage"s wipes out. So I can't use it.

I have also tried "io/text-streams" module but when I try to use this module in "firefox add-on builder"

```
var io = require("io/text-streams");
io.write("write it");

```

I am getting this error:

```
XPI not built

ModuleNotFoundError: unable to satisfy: require(io/text-streams) from /tmp/tmpePRdMr/addon-sdk-1.12/packages/sadaf2605-4/lib/main.js:2: Looked for it in: /tmp/tmpePRdMr/addon-sdk-1.12/packages/sadaf2605-4/lib/io/text-streams.js /tmp/tmpePRdMr/addon-sdk-1.12/lib/io/text-streams.js 

```

Most probably, I would need to install some packages, do the user who will be using my add-on, do they also need to install those packages on their browser?