Validate input decimal point

Input a number with one decimal point only

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.0/jquery.js"></script>
Enter a number with one(1) decimal point only<br />
<input type="text" id="decimalPt"> <br />

<input type="text" class="decimalPt roundUp" > <br />

<input type="text"  > <br />

JavaScript

$('#decimalPt, .decimalPt').keypress(function(evt) {
  evt = (evt) ? evt : window.event;
  var charCode = (evt.which) ? evt.which : evt.keyCode;
		if ($(this).val().indexOf('.') != -1) 
    return false;
  return true;
});

$('.roundUp').blur(function() {
  var value = parseFloat($(this).val());
  if (!isNaN(value)) {
    $(this).val(parseFloat(value).toFixed(1));
  }
});