JSFiddle - React, Tailwind, and code Playground

by Agony

HTML

<input><span></span>

CSS

@-webkit-keyframes blink {
    from, to { border-color: transparent }
    50% { border-color: black }
}

@-moz-keyframes blink {
    from, to { border-color: transparent }
    50% { border-color: black }
}

span{
    width:100px;
    height:100px;
    border-left:10px solid black;
    -webkit-animation: 1s blink step-end infinite;
    -moz-animation: 1s blink step-end infinite;
}

JavaScript

var element = document.createElement('input');
var blinker = document.getElementsByTagName('span');
element.value = blinker;

document.getElementsByTagName('input').append(blinker);