JSFiddle - React, Tailwind, and code Playground

HTML

<div class="box">
<textarea name="" id="text"></textarea>
<div class="word-counter">0/100</div>
</div>

CSS

.box {
width:500px;
border: 1px solid red;
position:relative;
display:table;
}
textarea {
width:500px;
height:80px;
padding-bottom: 20px;
}
.word-counter {
position:absolute;
bottom: 0;
right:0;
}

JavaScript

$('#text').keydown(function(e){
    var code=e.keyCode;
    var length=$(this).val().split(' ').length;
    if(length<=100)
    {
        $('.word-counter').text(length+'/100');
    }
    else
    {
        if(code!=37&&code!=38&&code!=39&&40&&code!=8&&code!=46)
        {
        return false;
        }
    }
});