<h3>Binary</h3>
<input type="text" placeholder="100110..." id="binary" />
<h3>Decimal</h3>
<input type="text" placeholder="100110..." disabled id="decimal" />
<script>
</script>

<a href="https://fjolt.com/article/javascript-converting-binary-to-decimal">Original Binary to Decimal Converter</a>

body {
    margin: 0;
    float: left;
    width: 100%;
    padding: 0 1rem;
    box-sizing: border-box;
    overflow-x: hidden;
    font-family: -apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Oxygen,Ubuntu,Cantarell,'Open Sans','Helvetica Neue',sans-serif;
    background: rgb(15 19 22);
    font-display: swap;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
    color: #fff;
}

a {
  color: white;
  display: block;
  margin: 2rem 0;
}

document.getElementById('binary').addEventListener('keyup', function(e) {
  let parseNumber = parseInt(document.getElementById('binary').value, 2);
  console.log(parseNumber);
  document.getElementById('decimal').value = parseNumber;
});