var idToHide; function hidePeer(peer) { chrome.storage.sync.get('idToHide', function(data) { idToHide = data.idToHide }); chrome.storage.sync.get('isExtensionOn', function(data) { if (data.isExtensionOn) { var x = document.querySelectorAll('[data-peer="'+peer+'"]'); x.forEach( function(val) { val.style.display = "none"; } ) } }); } //var interval = window.setInterval(function(){ hidePeer(idToHide) }, 500); var chatBody = document.getElementsByClassName("_im_peer_history im-page-chat-contain")[0]; chatBody.addEventListener('DOMNodeInserted', function() { hidePeer(idToHide); });