WebExtension/spawn.js

browser.runtime.sendMessage("Content_Loaded");
browser.runtime.onMessage.addListener(worker);

function test(msg)
{
		console.log(`Spawn: received message:${msg}`);

}

function worker(message)
{
		console.log("inside handler");
		console.log(message);

		setTimeout(() => {
				if(message != "Init")//on init only load page
				{
						let element = document.getElementsByClassName("yt-spec-button-shape-next yt-spec-button-shape-next--filled yt-spec-button-shape-next--mono yt-spec-button-shape-next--size-m")[0];
						if (element != null)
						{
								element.click();
								console.log("elements found");
						}
						else
						{
								console.log("element not found, already in Abo");
						}
						console.log(message);
				}
				browser.runtime.sendMessage("finished");
		},5000);
}