Roman Numerals

index.html

<div id="roman-numeral-converter" class="form-conversion">
  <div class="text-center mb-4">
    <h1 id="form-title" class="h3 mb-3 font-weight-normal">Roman Numerals</h1>
    <p id="instructions">Enter a number and convert it to a Roman numeral.</p>
  </div>

  <div class="form-group">
    <label for="input-number">Number</label>
    <input type="text" id="input-number" class="form-control" placeholder="Number" autofocus>
  </div>

  <button id="convert" class="btn btn-lg btn-primary btn-block">Convert</button>

  <div id="roman-numeral" class="form-group">
    <label for="output">Roman Numeral</label>
    <input id="output" type="text" class="form-control" autofocus>
    <small id="output-help" class="form-text text-muted">The number converted to a Roman numeral.</small>
  </div>
</div>

roman-numeral-converter.markdown

Roman Numeral Converter

A Pen by Stephen Bau on CodePen.

License.

roman-numerals.markdown

Roman Numerals

A Pen by Stephen Bau on CodePen.

License.

script.js

// A very elegant solution, thanks to melih on CodePen
// https://codepen.io/melih193/pen/Wxkqjv

$("button").click(function(){
var num = $('#input-number').val();
var roman = '';

var lookup = {M:1000,CM:900,D:500,CD:400,C:100,XC:90,L:50,XL:40,X:10,IX:9,V:5,IV:4,I:1};

  var i;
  
  for ( i in lookup ) {
    while ( num >= lookup[i] ) {
      roman += i;
      num -= lookup[i];
      console.log(i + ', ' + num + ', ' + lookup[i] + ', ' + roman);
    }
  }

  $("#output").val(roman);
  
});

scripts

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

style.css

:root {
  --input-padding-x: .75rem;
  --input-padding-y: .75rem;
}

html,
body {
  height: 100%;
}

body {
/*
  display: -ms-flexbox;
  display: flex;
  -ms-flex-align: center;
  align-items: center;
*/
  padding-top: 100px;
  padding-bottom: 100px;
  background-color: #f5f5f5;
}

.form-conversion {
  width: 100%;
  max-width: 420px;
  padding: 15px;
  margin: auto;
}

.form-label-group {
  position: relative;
  margin-bottom: 1rem;
}

.form-label-group > input,
.form-label-group > label {
  padding: var(--input-padding-y) var(--input-padding-x);
}

.form-label-group > label {
  position: absolute;
  top: 0;
  left: 0;
  display: block;
  width: 100%;
  margin-bottom: 0; /* Override default `<label>` margin */
  line-height: 1.5;
  color: #495057;
  border: 1px solid transparent;
  border-radius: .25rem;
  transition: all .1s ease-in-out;
}

.form-label-group input::-webkit-input-placeholder {
  color: transparent;
}

.form-label-group input:-ms-input-placeholder {
  color: transparent;
}

.form-label-group input::-ms-input-placeholder {
  color: transparent;
}

.form-label-group input::-moz-placeholder {
  color: transparent;
}

.form-label-group input::placeholder {
  color: transparent;
}

.form-label-group input:not(:placeholder-shown) {
  padding-top: calc(var(--input-padding-y) + var(--input-padding-y) * (2 / 3));
  padding-bottom: calc(var(--input-padding-y) / 3);
}

.form-label-group input:not(:placeholder-shown) ~ label {
  padding-top: calc(var(--input-padding-y) / 3);
  padding-bottom: calc(var(--input-padding-y) / 3);
  font-size: 12px;
  color: #777;
}

#roman-numeral {
  margin-top: 30px;
}

#convert {
  color: #fff;
}

#convert:active {
  background: #000;
}

styles

<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0/css/bootstrap.css" rel="stylesheet" />