JSFiddle - React, Tailwind, and code Playground

HTML

<table><tr class="s"><td/>asdf</td></tr><tr><td/>asdf</td></tr><tr><td/>asdf</td></tr><tr><td/>asdf</td></tr></table>

CSS

.s{
    background:red;
}

JavaScript

document.body.addEventListener('keydown',function(ev){
    var trs = document.querySelector('.s');
    if(ev.keyCode == 38 && trs.previousSibling){
        trs.className = '';
        trs.previousSibling.className = 's';
    }else if(ev.keyCode == 40 && trs.nextSibling){
        trs.className = '';
        trs.nextSibling.className = 's';
    }
});