<form action="javascript: void(0);">
  <input type="text" readonly value="readonly enable">
  <br>
  <input type="text" value="readonly disable">
  <br>
  <select name="" id="" readonly>
    <option value="">請選擇</option>
  </select>
  <br>
  <select name="" id="">
    <option value="">請選擇</option>
  </select>
  <br>
  <button readonly>readonly enable</button>
  <br>
  <button>readonly disable</button>
</form>
form [readonly] {
  pointer-events: none;
  background: gray;
}

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