如果选中单选按钮，则更改字段的只读状态，不进行jquery

Question

I have a form, I want to initially have some normal fields and some readonly fields. Then a radio button with two options, if it's the default option nothing changes, if they select the second then the readonly fields become editable.

I need to do this without jquery.

Here's the form

<form name="newstock" action="newstock-save.php" method="post">

<input type="radio" name="individual" value="1" checked> Fruit<br>
<input type="radio" name="individual" value="0"> Veges<br><br>

<table>
<tr>
    <td>Item name</td>
    <td><input type="text" name="item_name"></td>
</tr>
<tr>
    <td>Packing</td>
    <td><input type="text" name="packing_name" readonly></td>
</tr>
<tr>
    <td>Unit</td>
    <td><input type="text" name="packing_unit" readonly></td>
</tr>
</table>

Please assist

Answer 1

First, add the IDs in your HTML.

<form name="newstock" action="newstock-save.php" method="post">

<input type="radio" name="individual" value="1" id="individual1" checked> Fruit<br>
<input type="radio" name="individual" value="0" id="individual0"> Veges<br><br>

<table>
<tr>
    <td>Item name</td>
    <td><input type="text" name="item_name"></td>
</tr>
<tr>
    <td>Packing</td>
    <td><input type="text" name="packing_name" id="packing_name" readonly></td>
</tr>
<tr>
    <td>Unit</td>
    <td><input type="text" name="packing_unit" id="package_unit" readonly></td>
</tr>
</table>

Then, get the elements with getElementById, and add EventListeners in your JS.

const individual1  = document.getElementById("individual1"),
      individual0  = document.getElementById("individual0"),
      packing_name = document.getElementById("packing_name"),
      package_unit = document.getElementById("package_unit");

individual1.addEventListener("change", function(){
  packing_name.value = '';
  package_unit.value = '';
  packing_name.readOnly = true;
  package_unit.readOnly = true;
});

individual0.addEventListener("change", function(){
  packing_name.readOnly = false;
  package_unit.readOnly = false;
});

CodePen: https://codepen.io/anon/pen/vVyVGx