vk-mute/hide_element.js

{
    let idToHide;

    let chatBody = document.getElementsByClassName("_im_peer_history im-page-chat-contain")[0];

    chatBody.addEventListener('DOMNodeInserted', function(event) {
        if (event.target.className == 'im-mess-stack _im_mess_stack ') {
            chrome.storage.sync.get('idToHide', function(data) {
                idToHide = data.idToHide;
            });

            chrome.storage.sync.get('isExtensionOn', function(data) {
                if (data.isExtensionOn) {
                    if (event.target.dataset.peer == idToHide) {
                        event.target.style.display = "none";
                    }
                }
            });
        }
    });

    chrome.storage.sync.get('idToHide', function(data) {
        idToHide = data.idToHide;
    });

    // Try to hide until successful. Needed for page refresh.
    let hideInterval = setInterval(function () {
        chatBody = document.getElementsByClassName("_im_peer_history im-page-chat-contain")[0];
        for (let item of chatBody.children) {
            if (item.dataset.peer == idToHide) {
                if (item.style.display != "none") {
                    item.style.display = "none";
                } else {
                    clearInterval(hideInterval);
                }
            }
        }
    }, 200);
}