JSFiddle - React, Tailwind, and code Playground

HTML

<textarea name="" id="dd" cols="30" rows="10"></textarea>
<p>message length :<span id="msg"></span></p>

JavaScript

var elem = document.getElementById('dd');
var msg = document.getElementById('msg');
var len = 150;
function f(){
    var v = elem.value;
    if (v.length>len) elem.value = v.substring(0,len);
    else
        msg.innerHTML = v.length;
}

//elem.onchange = f;
elem.onkeyup = f;
elem.onkeydown = f;