Untitled fiddle

by bilbobaggins

HTML

<table>
  <tr>
    <td>
      <input type="text" placeholder="Name">
    </td>
    <td>
      <input type="text" placeholder="Please enter">
    </td>
  </tr>
</table>

JavaScript

document.addEventListener("input", function (e) {
    if (e.target.matches("input[type='text'], textarea")) {

        const td = e.target.closest("td");
        const nextTd = td?.nextElementSibling;
        const placeholderTextbox =
            nextTd?.querySelector("input[type='text'], textarea");

        if (placeholderTextbox) {
            placeholderTextbox.placeholder =
                "Please enter " + e.target.value;
        }
    }
});

document.addEventListener("change", function (e) {
    if (e.target.matches("select")) {

        const td = e.target.closest("td");
        const nextTd = td?.nextElementSibling;
        const placeholderTextbox =
            nextTd?.querySelector("input[type='text'], textarea");

        if (placeholderTextbox) {
            placeholderTextbox.placeholder =
                "Please select " +
                e.target.options[e.target.selectedIndex].text;
        }
    }
});