ONKEYUP in JS wont work

Hey.
ive got a problem. my on key up in JS wont work anymore after adding another NAME.js with a onkeyup function. Also This

window.onkeydown = function(e) {
        if(open) {
            if(e.which == 38) {
                setTimeout(() => {
                    if(selected > 1) {
                        selected = selected - 1;
                        var searchEles = document.getElementById("items").children;
                        for(var i = 0; i < searchEles.length; i++) {
                            if(searchEles[i].getAttribute("item-id") == selected) {
                                searchEles[i].scrollIntoView();
                            }
                        }
                    } else {
                        selected = maxbig;
                        var searchEles = document.getElementById("items").children;
                        for(var i = 0; i < searchEles.length; i++) {
                            if(searchEles[i].getAttribute("item-id") == selected) {
                                searchEles[i].scrollIntoView();
                            }
                        }
                    }    
                }, 100);
            }
            if(e.which == 40) {
                setTimeout(() => {
                    if(selected < maxbig) {
                        selected = selected + 1;
                        var searchEles = document.getElementById("items").children;
                        for(var i = 0; i < searchEles.length; i++) {
                            if(searchEles[i].getAttribute("item-id") == selected) {
                                searchEles[i].scrollIntoView();
                            }
                        }
                    } else {
                        selected = 1;
                        var searchEles = document.getElementById("items").children;
                        for(var i = 0; i < searchEles.length; i++) {
                            if(searchEles[i].getAttribute("item-id") == selected) {
                                searchEles[i].scrollIntoView();
                            }
                        }
                    }
                }, 100);
                
            }
            if(e.which == 13) {
                var searchEles = document.getElementById("items").children;
                for(var i = 0; i < searchEles.length; i++) {
                    if(searchEles[i].getAttribute("item-id") == selected) {
                       
                    }
                }
            }
            if(e.which == 8) {
                closeMenu()
            }

        }
    }

Wont work in Fivem, but in Chrome on my PC