JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="tbox"></text>
<button type="button" id="btn"  style="display:none;">push me</button>

JavaScript

$('#tbox').on('keydown keypress keyup',function(){
    if($('#tbox').val() !== '') {
        $('#btn').css({'display':'block'});
    } else {
        $('#btn').css({'display':'none'});
    }
});