var a; function betterlibrary() { if (a == undefined) try { a = document.getElementsByClassName("main-yourLibraryX-libraryContainer")[0]; console.log("setting a"); } catch (error) { } try { setTimeout(() => { document.getElementsByClassName("betterlibheader")[0].prepend(a); // document.getElementsByClassName("main-yourLibraryX-entryPoints")[0].appendChild(a); }, 100); console.log("did not catch"); } catch (error) { console.log("catch!!"); console.error(error); } }