EncodeURIComponent

<script type="text/javascript">
  function encode() {
    var v = document.getElementById('t').value;
    v = encodeURIComponent(v);
    document.getElementById('r').innerHTML = v;
  }
</script>
<input type="text" id="t" placeholder="Put your data here..." />
<button onclick="encode()">Encode</button>
<p id="r"></p>