var count = 1;
do {
function count_down(obj, count){
let element = document.getElementById('count'+ count);
element.innerHTML = 80 - obj.value.length;
if(80 - obj.value.length < 5){
element.style.color = "firebrick";
}else{
element.style.color = "#333";
}
}
count++;
} while (count < 20);
.text-input {
padding: 8px 16px;
width: 50%;
margin-bottom: 5px;
margin-top: 10px;
font-size: 20px;
font-weight: 700;
font-family: Raleway;
border: 1px solid dodgerblue;
}
<p><input placeholder="Title" id="bike-input-title" onkeyup="count_down(this, 3)" maxlength="80" class="text-input" name="bikeTitle" ></p>
<span id="count3" style="float: right; font-family: Raleway; font-size:20px; font-weight:600; margin-top:-5px;">80</span><br>
<input type="text" maxlength="5">
লাইভ ডেমো: jsfiddle.net/mcBbW/1