Converting a text input to a select with JavaScript

gistfile1.js

// Sometimes you need the page dimanically changes a texbox with a dropdown box. 
// On the example below we show you how to perform this work.
// source: http://www.apphp.com/index.php?snippet=javascript-converting-text-input-to-select

<div id="buy-buttons">
  <label>Quantity:</label>
  <input name="txtQuantity" id="txtQuantity" type="text" value="1" />
  <input type="submit" name="btnAddToCart" value="Add To Cart" id="btnAddToCart" />
</div>
 
<script>
// First way:
$("#txtQuantity").remove();
$("#buy-buttons").append('<select name="txtQuantity" id="txtQuantity"></select>');
$("#txtQuantity").append('<option value="1" selected="selected">1</option>' +
    '<option value="2">2</option>' +
    '<option value="3">3</option>' +
    '<option value="4">4</option>' +
    '<option value="5">5</option>');
 
// Second way:
$("#txtQuantity")
    .replaceWith('<select name="txtQuantity" id="txtQuantity">' +
        '<option value="1">1</option>' +
        '<option value="2">2</option>' +
        '<option value="3">3</option>' +
        '<option value="4">4</option>' +
        '<option value="5">5</option>' +
        '</select>');
</script>