Firefox web extension that enable a proxy if on mobile/cellular network

background.js

if (navigator.connection.type === "cellular") {
	browser.proxy.register(
		"pac.js"
	);
}

manifest.json

{
	"description": "Switching proxy if on mobile network",
	"manifest_version": 2,
	"name": "mobileproxy",
	"version": "0.1",
	"icons": {
		"48": "proxy.png"
	},
	"permissions": [
		"Network​Information",
		"proxy"
	],
	"background": {
		"scripts": [
			"background.js"
		]
	},
	"browser_specific_settings": {
		"gecko": {
			"id": "contact@email.com"
		}
	}
}

pac.js

function FindProxyForURL(url, host) {
    if (url.substring(0, 5) == 'http:' || url.substring(0, 6) == 'https:') {
        return "HTTP 127.0.0.1:8080";
    }
    return "DIRECT";
}

proxy.png