[javascript] Show how many characters remaining in a HTML text box using JavaScript

Try the following code for instance:

working code in jsfiddle.net

For textArea, use this:

<textarea id="txtBox"></textarea>
...
...

For textBox, use this:

<input type="text" id="txtBox"/>
<br>
<input type="text" id="counterBox"/>
<script>
 var txtBoxRef = document.querySelector("#txtBox");
 var counterRef = document.querySelector("#counterBox");
 txtBoxRef.addEventListener("keydown",function(){
  var remLength = 0;
  remLength = 160 - parseInt(txtBoxRef.value.length);
  if(remLength < 0)
   {
    txtBoxRef.value = txtBoxRef.value.substring(0, 160);
    return false;
   }
  counterRef.value = remLength + " characters remaining...";
 },true);
</script>

Hope this Helps!