When on YouTube click button to search for channel links on SocialBlade.

1. Visit YouTube channel
2. Bottom right link button
3. Click and it redirects in new tab https://socialblade.com/youtube/c/***/videos/highestrated

This is what I have so far, but no button appears in bottom right corner that I can click to visit socialblade stats.

// ==UserScript==
// @name             YouTube to SocialBlade
// @description      When on YouTube click button to search for SocialBlade stats.
// @namespace        stackoverflow.com
// @author           stackoverflow.com
// @license          MIT
// @include          https://www.youtube.com/c/*
// @include          https://www.youtube.com/channel/*
// @include          https://www.youtube.com/user/*
// @version          0.1
// @grant            none
// @icon             https://www.google.com/s2/favicons?domain=socialblade.com
// ==/UserScript==

(function() {
    'use strict';

    getChannelId();

    if (channelId) {

        let div = document.createElement('div');
        div.innerHTML = '<a id="socialbladeSearchButton">SocialBlade</a>';

        div.style.display = "inline-block";
        div.style.position = "fixed";
        div.style.right = "2%";
        div.style.bottom = "2%";
        div.style.zIndex = '9999';

        document.body.append(div);

        let icon = document.getElementById('socialbladeSearchButton');

        icon.style.background = 'white';
        icon.style.color = 'blue';
        icon.style.fontWeight = '800';
        icon.style.padding = '5px';
        icon.style.border = 'solid 2px black';
        icon.style.textDecoration = 'none';
        icon.style.fontSize = '14px';

        icon.href = 'https://socialblade.com/youtube/channel/' + channelId;
        icon.target = '_blank';
    }

    var channelId;

    function getChannelId() {
        let x = window.location.pathname;
        let arr = x.split('/');

        for (let i = 0; i < arr.length; i++){
            if (arr[i].substring(0,2) === 'channel' || arr[i].substring(0,2) === 'CHANNEL') {
                channelId = arr[i];
            }
        }
    }

})();

I think I'm having trouble understanding the function getChannelId() { part. I asked this question on another forum and someone replied

Call your function after you declared the function. channelId is just a string, it is not true or false, and you are not checking for anything, your if condition is very wrong. Why would you need a if condition for that in the first place? I would just get rid of it and of your whole function and for loop.

Any help is appreciate, thanks!